<PAGE>   1

                                                                   EXHIBIT 10.22

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

                   LABORATORY CORPORATION OF AMERICA HOLDINGS
                                   ("LABCORP")
                                MASTER AGREEMENT


This Agreement between TriPath Imaging. Inc. hereinafter referred to as TriPath
and Laboratory Corporation of America Holdings, ("LabCorp"), at LabCorp's option
"LabCorp" shall also refer to any or all of LabCorp's subsidiaries. This
Agreement sets forth the terms and conditions upon which TriPath will sell to
"LabCorp" and "LabCorp" will purchase various diagnostic products. The parties
agree as follows:

A.       In consideration of "LabCorp" purchasing from TriPath, the diagnostic
         products specified in the attached Product Addenda during the term of
         this Agreement, TriPath agrees to sell such diagnostic products to the
         "LabCorp" at the purchase prices specified. This is a Primary Source
         Agreement ,between the parties for products listed in the attached
         Addenda. This Agreement supersedes all prior contracts between the
         parties, and at LabCorp's option any prior contracts between TriPath
         and LabCorp's subsidiaries.

B.       "LabCorp", on a reasonable efforts basis, will notify TriPath in
         writing of all acquisitions, additions, and location changes. All
         previous agreements, between TriPath and the acquired "LabCorp" sites
         will, at "LabCorp"'s option, become null and void and this "LabCorp"
         Agreement will take effect. All acquisitions and additions shall be
         eligible for the current "LabCorp" pricing.

C.       The term of the Agreement shall commence on November 18, 1999 and
         remain in effect until *****************.

D.       TriPath shall ship to any "LabCorp" laboratory which orders diagnostic
         reagent who is authorized under this Agreement. Invoices should be
         mailed to the following address:

                                SEND INVOICES TO:

                              Laboratory Corporation of America Holdings
                              Accounts Payable Department
                              Caller 2280
                              Burlington, North Carolina 27216-2280

         Payment is ****************** for AutoCyte Prep Systems and component
         parts. Payment is ****************** for all disposables, (refer to
         Exhibit II "AutoCyte Prep System (TM)Disposables Addenda). "LabCorp" is
         taxable based on shipment destination and all applicable local/state
         taxes are the responsibility of "LabCorp". In those states where
         TriPath collects local/state sales taxes, TriPath will add these taxes
         to the invoices and remit to the appropriate taxing authority.

E.       Shipment shall be made*************************************************
         ******************. For the avoidance of doubt, TriPath will ship
         products *********** ********************************* to designated
         LabCorp processing Laboratories.

<PAGE>   2

         Express shipping charges incurred due to requested airfreight orders by
         LabCorp shall be borne by LabCorp.

F.       Neither party shall assign or transfer this Agreement without the
         consent of the other party, which consent shall not be unreasonably
         withheld or delayed.

G.       Notices and other communications permitted or required under this
         Agreement will be deemed to be properly given if in writing and either
         delivered by hand or mailed by First Class U.S. Mail, postage prepaid,
         addressed to the parties as follows:

         SELLER:             TriPath Imaging, Inc.
                             780 Plantation Drive
                             Burlington, NCCC 27215
                             Attention:  Ernie Knesel

         "LabCorp":          Laboratory Corporation of America Holdings
                             112 Orange Drive
                             Elon College, N. C. 27244
                             Attention:   Mrs. Gail Page
                              Carbon Copy to:
                             Laboratory Corporation of America Holdings
                             430 South Spring Street
                             Burlington, N.C. 27215
                             Attention:   Law Department

H.       This Agreement may not be amended or modified except by written
         agreement of both of the parties. Notwithstanding the above, if TriPath
         submits to LabCorp invoices at prices lower than those previously
         agreed to in this Agreement or Addenda, then LabCorp's sole
         responsibility shall be payment lesser of the invoice amount or the
         amount in the Agreement or Addenda.. In addition, in the event the
         invoice price is lower than the previously agreed price, the lower
         invoice price shall be the price for the remaining term of the
         applicable Agreement or Addenda. If minimum volumes or dollar
         expenditures specified in this agreement are not met, the parties will
         attempt to reach a new agreement as to prices. If no agreement is
         reached, TriPath may, as it's sole and exclusive remedy, terminate this
         agreement. In no event shall "LabCorp" be liable for monetary damages.

I.       TriPath will not be liable for any failure to perform under this
         Agreement due to strikes, fire, explosion, flood, riot, lock-out,
         injunction, interruption of transportation, unavoidable accidents,
         inability to obtain supplies at reasonable prices or diagnostic
         products set forth in this Agreement or any reason in this paragraph.
         Nothing shall prohibit "LabCorp" from obtaining the same or similar
         products from any source of "LabCorp"'s choosing during the period that
         TriPath is unable to perform under this Agreement.

J.       TriPath guarantees "LabCorp" the products supplied shall not be
         adulterated or misbranded within the meaning of the U.S. Food, Drug,
         and Cosmetic Act.

K.       TriPath and "LabCorp" will conduct quarterly business reviews to
         discuss technical performance of all products included in this
         Agreement. In the event that technical

<PAGE>   3

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

         problems are identified or a TriPath product is unavailable, "LabCorp"
         will notify TriPath of the problem in writing, TriPath will, within the
         course often (10) working days, identify an action plan to correct the
         problem and deliver this, in writing, to "LabCorp". If, after an
         additional twenty (20) working days, progress is not demonstrated in
         resolving the problem or product performance does not meet package
         insert claims, then "LabCorp" may discontinue use of that product
         without affecting the terms and conditions of the Agreement.

L.       This Agreement may be terminated by either party with or without cause
         at any time with ninety (90) days written notice unless there are
         quality or shipment problems. If quality or shipment problems occur,
         then Paragraph K (K on page 2) applies. Quality or shipment problems
         are defined as inconsistent shipments, inadequate product availability,
         products that do not meet package insert claims or performance
         specifications as published in the manufacturers' publications.

M.       If an individual product becomes standardized across all Laboratory
         Corporation of America Holdings laboratories, both parties will
         negotiate a price change for that product and amend or add a product
         addendum.

N.       Items defined as products listed on Addenda or added on Addenda (added
         at a later date) will have guaranteed pricing through the term of the
         agreement.

O.       If any terms of this Agreement are not met by "LabCorp" and the parties
         cannot agree on a resolution, TriPath may, as its sole and exclusive
         remedy, terminate this Agreement.

P.       TriPath warrants that during their applicable shelf life, the test will
         conform with the Specifications set forth in the package insert.
         FURTHERMORE, TRIPATH HEREBY REPRESENTS AND WARRANTS THAT***************
         ***********************************************************************
         *******************. TRIPATH HEREBY REPRESENTS AND WARRANTS THAT THE
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************

Q.       TriPath shall give "LabCorp" a 120 day written notification of any
         product changes.

R.       TriPath agrees to make the following Year 2000 Compliance Warranties
         with respect to any products covered by this Agreement (the
         "Products").

         1.       DEFINITIONS.  As used in this Section:

         a.       "Date Data" shall mean any data or input which includes an
                  indication of or reference to date.

         b.       "Four Digit Year Format" shall mean a format that allows entry
                  or processing of a four digit year in which the first two
                  digits will designate the century and the second two digits
                  shall designate the year within the century.

<PAGE>   4

         c.       "Leap Year" shall mean the year during which an extra day is
                  added in February. Leap Year occurs in all years divisible by
                  400 or evenly divisible by 4 and not evenly divisible by 100.

         d.       "Year 2000 Capabilities" shall mean that the Products:

                          (i)     will manage, store and manipulate Date Data,
                                  including single-century and multi-century
                                  formats, and will not cause an abnormal ending
                                  within applications or format incorrect values
                                  or invalid results involving such dates; and

                          (ii)    ensures that all Date Data fields, all
                                  date-related user interface functionalities
                                  and all date-related data interface
                                  functionalities include the indication of
                                  century.

         e.       "Year 2000 Compliant" or "Year 2000 Compliance" shall mean
                  that the Date Data outside of the range 1990-1999 will be
                  correctly processed in any level of computer hardware or
                  software including, but not limited to, microcode, firmware,
                  application programs, files and databases.

         2.       YEAR 2000 COMPLIANCE WARRANTIES.

         a.       TriPath represents and warrants that the Products are designed
                  to be used prior to, during, and after the calendar year 2000
                  A.D., and that the Products will operate during any such time
                  period without error relating to Date Data, including, but not
                  limited to, any error that relates to, or is the product of,
                  Date Data which represents or references different centuries
                  or more than one century.

         b.       Without limiting the generality of the foregoing, TriPath
                  further represents and warrants:

                          (1)     that the Products will not abnormally end or
                                  provide invalid or incorrect results as a
                                  result of Date Data, including, but not
                                  limited to, Date Data which represents or
                                  references different centuries or more than
                                  one century;

                          (2)     that the Products have been designed to ensure
                                  Year 2000 Compliance, including, but not
                                  limited to, Date Data century recognition,
                                  calculations which accommodate same-century
                                  and multi-century formulas and date values,
                                  and Date Data interface values that reflect
                                  the century;

                          (3)     that the Products are and will continue to be
                                  Year 2000 Compliant; that all date processing
                                  by the Products will include Four Digit Year
                                  Format and recognize and correctly process
                                  dates for Leap Year; and that all sorting data
                                  that includes a year category shall be done
                                  based on the Four Digit Year Format code; and

                          (4)     that the Products include "Year 2000
                                  Capability".

<PAGE>   5

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

         TriPath agrees to pay liquidated damages in the amount of $_____ per
         day for each day the Products fail to maintain and uphold the Year 2000
         Compliance Warranties described in this Section.

S.       TriPath agrees to defend, indemnify, and hold "LabCorp" and
         subsidiaries, directors, officers, employees, an agents wholly harmless
         from and against third-party claims, losses, DAMAGES, lawsuits,
         settlements, demands, causes, judgments, expenses, and cost (including
         reasonable attorney fees) arising OR ALLEGED under or in connection
         with this Agreement or LABCORP'S USE OF PRODUCTS UNDER THIS AGREEMENT
         in the event that such cost and liabilities are caused by a) TriPath 1
         reach of any of its warranties in this Agreement, b) the failure of
         products to function properly for "LabCorp's intended use, c) any
         negligence or willful misconduct of TriPath, or d) any other liability
         resulting from "LabCorp's use of the PRODUCTS. However, such rights to
         indemnify shall not apply to the extent that such claim, loss, lawsuit
         or settlement results from "LabCorp's sole negligence or willful acts
         including the sole negligence of LabCorp employees.********************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         **********************************

T.       ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         *****************************************

U.       TriPath acknowledges that LabCorp has a proprietary interest in its
         legal and business name and REPUTATION. Therefore, TriPath agrees that
         it shall not use LabCorp's name nor shall TriPath mention or describe
         this Agreement or its relationship with LabCorp in any press release,
         advertising, marketing, and promotional materials or other publications
         or materials without first obtaining the prior written approval of
         LabCorp's Senior Vice-President of Automation and Diagnostics. A
         violation of this paragraph shall be considered a material breach of
         this Agreement by LabCorp, and LabCorp shall be entitled to pursue any
         and all legal or equitable remedies, including an injunction, as a
         result of such breach.

  IN THE EVENT OF ANY INCONSISTENCIES BETWEEN THIS AGREEMENT AND THE APPENDED
            TERMS & CONDITIONS, THIS MASTER AGREEMENT SHALL CONTROL.

<PAGE>   6

LABORATORY CORPORATION OF                TRIPATH IMAGING, INC.
AMERICA HOLDINGS


By:______________________________        By:____________________________________


Title:___________________________        Title:_________________________________


Date:____________________________        Date:__________________________________

<PAGE>   7

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

  PRODUCT ADDENDUM A TO LABORATORY CORPORATION OF AMERICA HOLDINGS ("LABCORP")

             MASTER AGREEMENT WITH TRIPATH IMAGING, INC. ("TRIPATH")

           PRODUCTS COVERED IN THIS ADDENDUM: AUTOCYTE PREP SYSTEM(TM)
                            AND RELATED DISPOSABLES

                       DATE OF ADDENDUM: NOVEMBER 18, 1999


         As part of the above-referenced agreement, TriPath will provide LabCorp
and its subsidiaries with the AutoCyte PREP SystemTM ("PREP") and related
disposables for gynecological ("GYN") cytology. The terms and conditions of sale
are as stated in the Master Agreement, along with the following terms and
conditions.


1.       PRODUCTS COVERED BY THIS AGREEMENT, AND RELATED PRICING:


         ***********************************************************************
         *                                                                     *
         *                                                                     *
         *                                                                     *
         *                                                                     *
         ***********************************************************************


     (1)      As more fully described in Exhibit I
     (2)      As more fully described in Exhibit II


2.        UPDATING AND RESTORATION: TriPath has agreed to update and restore to
          the current GYN approved specifications all AutoCyte PREP Systems
          owned by LabCorp at TriPath expense. This includes the replacement of
          all tubing, valves, slide platters and installation of the new Gyn
          software. This will be accomplished by November 15, 1999 on the ***
          instruments purchased by LabCorp prior to 1996 for use with non-gyn
          preparations.

3.       ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************
         ***********************************************************************

<PAGE>   8

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

         ***********************************************************************
         *******************************************************

4.       ADDITIONAL SUPPORT PROVIDED BY TRIPATH: TriPath agrees to support
         LabCorp in the following ways:

         a.       Technical training at TriPath for a pathologist,
                  cytotechnologist and prep technician from each site. TriPath
                  will pay for all meals, lodging and training at its site.
                  LabCorp will pay for all transportation.

         b.       On-site training of additional Cytotechnologists and technical
                  support as REASONABLY REQUIRED BY LABCORP to initiate the
                  technology at each LabCorp site at TriPath expense.

         c.       Sales and promotional support including sales training and
                  joint calling of key accounts for each LabCorp region. TRIPATH
                  SHALL ADD A MINIMUM OF TEN ADDITIONAL TECHNICAL SALES
                  SPECIALISTS TO ITS STAFF WITHIN 90 DAYS OF SIGNING THIS
                  AGREEMENT FOR PURPOSES OF MARKETING TRIPATH'S SERVICES TO
                  THIRD PARTIES.

         d.       TriPath will conduct regional sales training as requested by
                  regional LabCorp management and will work to support LabCorp
                  sales representatives in the field as mutually agreed upon by
                  the parties. This training SHALL PROVIDE THE LABCORP SALES
                  REPRESENTATIVES WITH THE NECESSARY KNOWLEDGE OF THE FEATURES
                  AND BENEFITS OF THE TRIPATH PRODUCTS.

         e.       THROUGHOUT THE TERM OF THIS AGREEMENT, TRIPATH SHALL RETAIN A
                  COMPANY WITH SIGNIFICANT REIMBURSEMENT EXPERIENCE TO ASSIST
                  THE PARTIES WITH NON-PAYMENT OR REIMBURSEMENT ISSUES.

         5.       PAYMENT TERMS:

         a.       LabCorp will determine on a lab-by-lab basis the amount of lab
                  supplies that it will purchase by issuance of a purchase order
                  and which TriPath will then ship and invoice according to the
                  Terms and Conditions of the purchase order. TriPath and
                  LabCorp agree to make the shipment amounts based upon an
                  estimated usage, but never less than a 480 test kit. The
                  shipment quantities will be increased once experience
                  demonstrates levels of usage.

         b.       **************************************************************
                  **************************************************************
                  **************************************************************
                  **************************************************************
                  **************************************************************
                  **************************************************************
                  **************************************************************
                  **************************************************************
                  ******************************

<PAGE>   9

         6.       WARRANTY:

                  a. EQUIPMENT: TriPath warrants that the AutoCyte PREP System
                  and all component parts will perform in accordance with
                  product specifications and FDA-approved product labeling for a
                  period of twelve (12) months after the purchase date, provided
                  that LabCorp uses no reagents, consumables and/or accessories
                  on the Equipment other than those from TriPath or its
                  authorized agents. During such twelve (12) month period, at no
                  cost to LabCorp, TriPath or TriPath appointed personnel shall
                  service, alter or replace the Equipment and/or accessories
                  which are necessary to keep the equipment in good running
                  order, excluding consumable items which require replacement
                  with normal use. No other persons are authorized to perform
                  service on the EQUIPMENT. Excepting repair expense arising
                  from normal use, LabCorp shall reimburse TriPath or pay for
                  the reasonable expenses of repairing any damage or alteration
                  to the Equipment caused by LabCorp, it's employees, agents,
                  contractors or any unauthorized personnel. TriPath will
                  provide at no charge to LabCorp one scheduled preventive
                  maintenance visit per system after six (6) months of
                  operation.

                  b. REAGENTS: TriPath warrants that for a period of six (6)
                  months after the date of shipment from TriPath, all
                  disposables sold by TriPath to LabCorp shall, under normal
                  use, materially conform with TriPath's published
                  specifications and FDA-approved product labeling as of the
                  date of shipment of the Reagent and shall be free from
                  manufacturing and material defects.

                  c. WARRANTY CONDITIONS PRECEDENT: TriPath shall bear no
                  responsibility for correcting, curing, or otherwise remedying
                  any nonconformity or defect in the AutoCyte PREP System (the
                  "Product") (or any other breach with respect to the condition
                  or operation of the Products) if (1) with respect to Equipment
                  and Software, such Product is not installed and maintained by
                  TriPath or its authorized agents; (2) the Product is not
                  OPERATED IN A MANNER CONSISTENT WITH PACKAGE INSERT AND
                  PRODUCT SPECIFICATIONS; (3) the Product incorporates spare or
                  replacement parts or utilizes reagents other than those
                  purchased from or recommended by TriPath.

7.        SOFTWARE LICENSE: TriPath provides LabCorp a nontransferable,
          nonexclusive, royalty free license to the software KNOWN AS THE PREP
          GYN OPERATING SOFTWARE. LabCorp may not copy, modify, decode, reverse
          engineer, decompile or disassemble the Software for any purpose.

                  a.       Title and Ownership. TRIPATH REPRESENTS AND WARRANTS
                           THAT IT HAS THE UNENCUMBERED RIGHT TO LICENSE THE
                           SOFTWARE AND SUCH LICENSE DOES NOT VIOLATE THE RIGHTS
                           OF ANY THIRD PARTY. All title and ownership of
                           proprietary and intellectual property rights in the
                           Software and related documentation are and shall at
                           all times remain the sole
                           and exclusive property of TriPath.

                  b.       License Term. The license granted under this
                           Agreement shall commence upon delivery of the
                           Software to LabCorp by TriPath and shall continue
                           indefinitely unless terminated sooner. LabCorp may

<PAGE>   10

                           terminate this license at any time by written notice
                           to TriPath. TriPath may terminate this license at any
                           time upon the delivery of written notice to LabCorp
                           if LabCorp falls to fulfill any of its material
                           obligations hereunder and does not cure such failure
                           within thirty (30) days following written notice
                           thereof.

Laboratory Corporation of America Holdings     TriPath Imaging, Inc.

By:_______________________________________     _________________________________

<PAGE>   11

                                    EXHIBIT I

AUTOCYTE PREP SYSTEM(TM) COMPONENTS AND SPECIFICATIONS

The AutoCyte PREP System is a batch oriented sample-processing device capable of
producing up to 48 stained thin layer slides in approximately one hour. The
AutoCyte PREP System includes the PREP sample processor instrument and
accessories, a personal computer with PREP GYN operating software pre- installed
and a Hettich programmable centrifuge capable of performing all functions
necessary to prepare cytological samples for the AutoCyte PREP System

         1.       PREP SAMPLE PROCESSOR INSTRUMENT
                            -   Quad assembly with tips
                            -   Base Plate
                            -   (4) Interlocking Slide Racks
                            -   Disposable tip rack, holder and loading tool
                            -   Waste trough
                            -   Specimen Accessioning Rack
                            -   (2) Vacuum pumps and tube vac head
                            -   Slide rack for 25 slides
                            -   Slide coat tank with lid
                            -   6 position bottle holder
                            -   (2) 500m1 cleaning bottles
                            -   0-5ml Dispenser
                      Voltage:  120v or 220v / 50-60 Hz
                      Power: 800 VA
                      Weight:  168 lbs.
                      Dimensions: Height- 30"      Width- 38"       Depth- 25"
                      Throughput: Up to 48 Stained thin layer slides per run

         2.       SYSTEM CONTROL MODULE
                            - IBM compatible PC (80386 or greater)
                            - 14 inch color monitor
                            - Qwerty keyboard
                            - IBM compatible mouse
                      Voltage: 120v or 220v / 50-60 Hz
                      Power: 50-60 W
                      Weight: Subject to change based on availability

         3.       HETTICH PROGRAMMABLE CENTRIFUGE
                            - (4) Red plastic buckets
                            - (4) 12 place tube holder
                            - (4) Centrifuge bucket covers
                      Voltage:  120 v or 220v / 50C60 Hz
                      Power:  400 W
                      Weight:  110 lbs.
                      Dimensions: Height- 17"  Width- 24"   Depth- 21"

<PAGE>   12

                    *CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
           SECURITIES AND EXCHANGE COMMISSION.  ASTERISKS DENOTE SUCH OMISSIONS.

                                   EXHIBIT II

                      AUTOCYTE PREP SYSTEM(TM) DISPOSABlES

EXHIBIT B

   ADDENDUM TO EXHIBIT D FROM ORIGINAL CONSIGNMENT OF EQUIPMENT AND PURCHASE
                        OF RELATED DISPOSABLES AGREEMENT


  PART #                        DESCRIPTION                              PRICE
  ------                        -----------                              -----

GYN-0480DS               GYN 480 TEST KIT LABPACK                      $********
               THIS KIT CONTAINS DISPOSABLES NECESSARY TO PRODUCE
               480 GYN THIN-LAYER SLIDE PREPARATION, AS FOLLOWS:
               Slide Coat Reagent (275ml)
               Density Reagent (4 x 480ml)
               Hematoxylin (2 x 480ml)
               Orange G Stain (2 x 480ml)
               Modified EA Stain (2 x 480ml)
               Settling Chambers (480)
               Cyringes (500)
               Slides (500)
               Centrifuge Tubes (500)
               Disposable Transfer Tips (480)
               Aspirator Tips (200)

ADDITIONAL ITEMS THAT CAN BE PURCHASED SEPARATELY:

GYN-0500-C     500 GYN BRUSH & VIAL KIT                                $********
05CR000029     ALCOHOL RINSE SOLUTION (3600ML)                         $********
05CR000031     ALCOHOL RINSE SOLUTION (480ML)                          $********
90CR000006     SLIDE COAT REAGENT (275ML)                              $********
90CR000037     GYN PRESERVATIVE FLUID (3600ML)                         $********
90CR000001     GYN PRESERVATIVE FLUID (480ML)                          $********
80CR000022     BUFFERED WATER                                          $********