The List of Presented Cases
1. Foreign-body granuloma
2. Esophageal diverticulum
3. Median cervical cyst
4. Lateral cervical cyst
5. Hypopharyngeal piriform sinus fistula
6. Subacute thyroiditis
7. Hashimoto’s disease (nodular type)8. IgG4-related thyroiditis
9. Graves’ disease (post-radiation
therapy)
10. Black thyroid
11. Needle trace
12. Thyroid Cyst
13. Adenomatous goiter (follicularpattern)
14. Adenomatous goiter (papillary
pattern)
15. Dyshormonogenetic goiter
16. Follicular adenoma (mucinous
stroma)17. Follicular adenoma, oxyphilic cellvariant
18. Atypical adenoma
19. Widely invasive follicular carcinoma
20. Widely invasive follicular carcinoma,
oxyphilic cell variant
21. Follicular carcinoma (needle tract
implantation)
22. Hyalinizing trabecular tumor
23. Papillary carcinoma, conventional
24. Papillary carcinoma, follicularvariant
25. Papillary carcinoma, macrofollicularvariant

26. Papillary carcinoma, tall cell variant
27. Papillary carcinoma, cribriform
variant
28. Papillary carcinoma, Warthin tumorlike
29. Papillary carcinoma, solid variant
30. Papillary carcinoma, oxyphilic cellvariant
31. Papillary carcinoma, diffuse
sclerosing variant
32. Papillary carcinoma, cystic
33. Papillary carcinoma, polycystic
34. Papillary carcinoma, fasciitis-likestroma
35. Papillary carcinoma withsquamous cell metaplasia
36. Papillary carcinoma (hobnail cell)
37. Poorly differentiated carcinoma
38. Anaplastic carcinoma
39. Anaplastic carcinoma withosteoclast-like multinucleated giant cell
40. Medullary carcinoma (aggressive)
41. Medullary carcinoma (spindle cell)
42. Medullary carcinoma (pseudotubules)
43. MALT lymphoma
44. Diffuse large B-cell lymphoma
45. ITET/CASTLE
46. Parathyroid cyst
47. Parathyroid cyst and Parathyroid
adenoma
48. Parathyroid adenoma

Case 1

Foreign-body granuloma
suture thread

multinucleated giant cell

fibroblasts

A nodular lesion (arrow) appeared 2 years after total thyroidectomy for papillary carcinoma.
Thyroglobulin level in needle washout fluid was low. In the cytological smear, foreign-bodies (suture
thread), multinucleated giant cells, histiocytes, neutrophils, and fibroblasts are seen.

Case 2Esophageal diverticulum

bacteria
LBC

LBC
food debris

A lesion is usually present at the posterior of left thyroid lobe. As it looks like thyroid nodule
ultrasonographically, FNA may be performed. Squamous cells, bacteria, and food debris are seenin the cytological smear.

Case 3

Median cervical cyst

Unilocular
cyst
located at
the upper
portion oftheisthmus.

LBC

LBC

cilia

Cytology: LBC smears usually exhibits more epithelial cells than conventional smears in fluid
materials. Therefore, we recommend the former for cystic lesions. Numerous foamy cells and asmall number of squamous cells are seen on the smear.
Histology: The cyst wall is composed of granulation tissue and an aggregation of histiocytes.
Thyroid tissue is not present. The inner surface is focally covered with squamous cells and ciliatedcells (arrow).

Case 4Lateral cervical cyst

LBC

LBC

Whitish-yellow viscous liquid was aspirated.
Squamous cell, anucleate squamous cells, andnecrotic debris are seen.

Case 5Hypopharyngeal piriform sinus fistulapharyngoesophagography

The left upper lobe is the mostprevalent.

Acute suppurative thyroiditis is frequently
caused by this lesion. In addition to numerous
neutrophils, ciliated cell and squamous cells
may be seen.

Case 6

Subacute thyroiditis

Ill-defined low-echoic lesion is present in the left
lobe. Grossly, irregular-shaped whitish nodule areseen.

multinucleated giant cellepithelioid cell

Cytology: Multinucleated giant cells, lymphocytes, histiocytes, and epithelioid cell are seen.
Histology: Subacute thyroiditis is characterized by granulomas composed of epithelioid cells andmultinucleated giant cells, associated with lymphocytic infiltration and fibrosis. The granulomas focus
on an individual thyroid follicle.

Case 7

Hashimoto’s disease (nodular type)Ill-defined, low-echoic lesion (white arrow) isseen in the right lobe. Grossly, it is whitish andsolid nodule (red arrow).
LBC

multinucleatedgiant cell
LBC

aggregation of lymphocytes

Cytology: Oxyphilic cells show sheet-like, trabecular, and microfollicular clusters. N/C ratio is notincreased, and intranuclear cytoplasmic inclusions are not observed. Lymphocytes are noticed on the
background and within oxyphilic cell clusters. In LBC smear, oxyphilic cells are relatively increased
because of a loss of lymphocytes. Some multinucleated giant cells are seen.
Histology: The nodule is consistent with Hashimoto’s thyroiditis, except for encapsulation. The follicles
composed of oxyphilic cells are mostly small-sized and contain multinucleated giant cells.

Case 8IgG4-related thyroiditis
frontal plane

IgG4

Cytology: The findings are consistent with Hashimoto’s thyroiditis. Oxyphilic cells show sheet-like,small cluster, and trabecular clusters. Follicular pattern is not observed. Nuclear grooves areoccasionally observed. Intranuclear cytoplasmic inclusion is not seen. Lymphocytes and plasma
cells are seen on the background and within oxyphilic cell clusters.
Histology: Hashimoto’s thyroiditis with prominent plasma cell infiltration and fibrosis indicate IgG4related thyroiditis.

Case 9Graves’ disease (post-radiation therapy)
frontal plane

TTF-1

cytokeratin
AE1/AE3

The thyroid is occupied with band-like hyaline fibrous connective tissue. Small-sized follicles
composed of large atypical follicular cells with hyperchromatic nuclei and prominent nucleoli areseen. The presence of the bizarre follicular cells probably results from preceding radiation therapy.

Case 10

Black thyroid

Follicular cells contain black to brown pigments. The pigments are also observed in the lumen of
the thyroid follicles, individually or phagocyted by macrophages.

Case 11

Needle trace

A variety of histological reactions are caused by FNA. The findings change differ with the duration
between aspiration and operations. Granulation tissue with cholesterol crystals is seen in this case.
The size is almost same to a gauge of the needle (22G). It looks like involuted nodular goiter.

Case 12

Thyroid Cyst

Ultrasound reveals a unilocular cyst. The wall isthick and associated with calcification. Grossly,
cyst wall is brownish, indicating hemorrhage.

LBC

LBC

anucleate squamous cell

Cytology (LBC): There are histiocytes, proteinaceous materials, degenerated RBC, and a few
anucleated squamous cells. According to the Bethesda system, this case is categorized into
“Nondiagnostic” or “Unsatisfactory”.
Histology: The cyst wall is composed of granulation tissue surrounded by fibrotic tissue. Fibrinmaterials and hemosiderin-laden macrophages are seen in the lumen.

Case 13 Adenomatous goiter (follicular pattern)
frontal plane

The cut surface of the nodules are variable.
Aspiration cytology was performed from theencapsulated and solid nodule (arrow).

Cytology: Follicular cells are embedded within abundant colloid materials. The follicular cells show
sheet-like and follicular clusters. The nuclei are variable in size and hyperchromatic. N/C ratio is
not high. Naked and isolated follicular cells look like lymphocytes.
Histology: The nodules are composed of various-sized follicles.

Case 14 Adenomatous goiter (papillary pattern)

Ultrasonography reveals a well-defined, slightly
hypoechoic, homogeneous nodule.

papillarycluster

Cytology: Follicular cells show papillary and follicular clusters. The nuclei are round to ovoid inshape. There are no nuclear findings characteristic of papillary carcinoma.
Histology: Papillary growth are seen, but nuclear findings indicating papillary carcinoma are notobserved.

Case 15

Dyshormonogenetic goiterweight 475.4g

frontal plane

The thyroid is markedly
increased in size due tomultiple goiter.

thyroglobulin

signet ring cell-like cell
cf. normal thyroid

The nodules are composed of monotonous microfollicles mimicking follicular adenoma or
carcinoma. However, MIB-1 labeling index of the nodules is less than 1% and vascular invasion
and/or distant metastasis are not detected. One nodule exhibits follicular cells with signet ringcells appearance. The thyroid follicles located in non-nodular area are composed of enlarged
follicular cells and the lumen is not filled with colloid (empty). These findings are characteristic of
thyroglobulin gene mutation. Immunohistochemically, the thyroglobulin is accumulated in thecytoplasm of the follicular cells.

Case 16 Follicular adenoma (mucinous stroma)
Encapsulated nodulewith cystic formation isseen in the right lobe.
Solid portion of thenodule is translucent.
TTF-1 LBC

capillary plexus

Hyaline droplet

Cytology: The background is not colloid but mucinous. Capillary plexus is noted. Small follicular
cells exhibit cell clusters, pseudo-cribriform pattern, or isolated pattern. Intracytoplasmic hyaline
droplet is seen, but the meaning is obscure.
Histology: Follicular adenoma is lobulated and has abundant stromal mucin.

Case 17

Follicular adenoma, oxyphilic cell variant

Encapsulated nodule contains small cystic area.
Cut surface of the nodule is brownish.

capillary

Cytology: Oxyphilic cells appear as sheet-like, trabecular, or small follicular clusters. The capillaries
are embedded within the cell clusters. The cytoplasm is abundant and granular. The nuclei show
various sizes, hyperchromasia, granular chromatin pattern, enlarged nucleoli, and binuclei.
Histology: Encapsulated nodule is composed of oxyphilic cells showing microfollicular andtrabecular patterns. Papillary growth is focally seen, but no nuclear feature consistent withpapillary carcinoma is observed.

Case 18

Atypical adenoma

A well-defined yellowish nodule is locatedin the right lobe.

Cytology: Small round cells with high N/C ratio appear as microfollicular pattern. The sizes of thefollicles are imagined from those of hyaline colloid. The findings are consistent with follicularneoplasm. Large cells with hyperchromatic nuclei are scattered.
Histology: Large and bizarre atypical cells are observed, but infiltrative growth, large prominent
nucleoli, mitotic figures, necrosis, and neutrophilic infiltration suspecting malignancy are notpresent. MIB-1 labeling index was less than 1%.

Case 19
capsular invation

Widely invasive follicular carcinoma
frontal plane

The tumor is lobulated and solid.
Macroscopically, capsular invasion isapparent (arrow).

capillary

Cytology: Monotonous follicular cells appear as microfollicular pattern. They tend to aggregate
around capillaries (Upper left). The microfollicles are three-dimensional.
Histology: Carcinoma cells show trabecular and microfollicular growth patterns. The stroma is richin capillaries.

Case 20

Widely invasive follicular carcinoma,
oxyphilic cell variant

The tumor is encapsulated, but apparent
capsular invasion are visible at two portions (7and 11 o’clock.) The cut surface is brownish.

Cytology: The smear is mainly composed of oxyphilic cells that have abundant, thick, granular, anddensely lightgreen-stained cytoplasm with distinct cell border. Binuclei are scattered.
Histology: Oxyphilic cells show microfollicular and trabecular growth patterns. Stromal edema is
focally seen.

Case 21 Follicular carcinoma (needle tract implantation)

The patient has a history with the resection of
thyroid nodule 3 years ago. Two nodules (arrow)appeared in the subcutaneous tissue of the neck.

MIB-1

Cytology: The smear is cellular. Carcinoma cells show microfollicular, trabecular, and threedimensional clusters. The nuclei are enlarged and hyperchromatic.
Histology: The encapsulated nodule is located in the subcutaneous adipose tissue and shows
capsular invasion. One nodule is lobulated. There are no findings consistent with the nuclei ofpapillary carcinoma. Well-differentiated thyroid carcinomas revealing needle tract implantation
usually show high MIB-1 labeling index.

Case 22

Hyalinizing trabecular tumor

frontal plane
The margin of the tumor is not perfectly smooth. Color
Doppler shows hypervascular flow, called “tumor
inferno”. Cut surface is solid and yellowish white.
LBC

MIB-1

Cytology: The hyaline materials are located at the center of cell clusters and radially elongated. The
border between hyaline materials and the tumor cells is obscure. Cell border of the tumor cells is
indistinct. Intranuclear cytoplasmic inclusions (ICIs) and yellow bodies (YBs) (red arrow) are seen.
Histology: The tumor cells mainly show trabecular pattern with intra- and inter- trabecular hyalinematerials. ICIs and YBs (yellow arrow) are seen. Psammoma bodies are not located in the stroma
but the lumen.

Case 23

Papillary carcinoma, conventional

The tumor is well-demarcated, but the border isirregular. Tiny calcification is seen. The size of thetumor is less than 1cm (microcarcinoma).
LBC

papillary cluster

LBC

convoluted nuclei

papillary cluster
without stromal component

Cytology: Papillary tissue fragments associated with stroma component are seen. Duct-likeappearance means papillary cluster without stromal component (LBC). Convoluted nuclei arecharacteristic of papillary carcinoma in SurePath smear.
Histology: Tumor cells mainly show papillary growth. Ground glass chromatin, nuclear grooves,intranuclear cytoplasmic inclusions, nuclear overlapping are seen.

Case 24

Papillary carcinoma, follicular variant

A solid nodule with calcification is seen at theupper portion of the left lobe. Cut surface ishomogeneous and somewhat shiny, like follicularneoplasm.

Cytology: Tumor cells show follicular clusters. Intranuclear cytoplasmic inclusions, nuclear grooves,lobulated nuclei, irregular-shaped nuclei are seen.
Histology: Tumor cells mainly show follicular pattern, and have nuclear features consistent withpapillary carcinoma, except for ground glass nuclei.

Case 25 Papillary carcinoma, macrofollicular variant

A encapsulated tumor like follicular neoplasm
is seen.

Cytology: There are abundant colloid in the background. Tumor cells appear as two-dimensional
sheet. Nuclear grooves, irregular-shaped nuclei, and crowded nuclei are seen.
Histology: Encapsulated follicular lesion composed mainly of large follicles showing ground glass
nuclei, nuclear overlapping, irregular-shaped nuclei, and nuclear groove.

Case 26

Papillary carcinoma, tall cell variant

The tumor is solid, whitish, and invasive.
elongated cytoplasm
ropy colloid

multinucleated giant cell

Cytology: The tumor cells are tall or polyhedral, and show densely stained abundant cytoplasm, low
N/C ratio, and elongated cytoplasm (tail formation).
Histology: The carcinoma cells show trabecular or papillary growth. Most of the tumor arecomposed of tall columnar cells whose heights are more than three times as tall as their width.

Case 27

Papillary carcinoma, cribriform variant
frontal plane

Well-demarcated, whitish tumor occupies rightlobe. Grossly, it looks like follicular neoplasm.
β-catenin

LBC

ER

β-cateninERmorule
The case is teenage female.
Cytology: The smear is cellular. Large solid clusters with window (consistent with empty lumen) areseen. Nuclear chromatin is not ground glass but granular. The tumor cells are tall columnar. The
nuclei are short spindle.
Histology: Cribriform pattern without colloid, papillary growth of tall cells, solid growth composedof spindle cells, and morules with peculiar nuclear clearing are seen.
Immunostaining: β-catenin is positive for the nuclei and cytoplasm. ER and PgR are positive
except for morules.

Case 28

Papillary carcinoma, Warthin tumor-likeA nodule with indistinct border is seen in the
thyroid showing Hashimoto’s thyroiditis.

Cytology: There are a large number of lymphocytes and plasma cells in the background. Tumor
cells show abundant, densely stained cytoplasm. The nuclei are irregular shaped, like those ofhistiocytes.
Histology: Eosinophilic tall columnar tumor cells show papillary growth. The stroma contains
lymphocytes and plasma cells. Lymph follicles are scattered.

Case 29

Papillary carcinoma, solid variant

A nodule with calcification is present in theleft lobe.

LBC

Cytology: Tumor cells exhibit intranuclear cytoplasmic inclusions and nuclear grooves. The clue
indicating solid variant is a patternless pattern (neither sheet, follicle, nor papillary pattern).
Histology: Tumor cells mainly proliferate as alveolar structure. The tumor cells are morphologicallysimilar to conventional papillary carcinoma. Poorly differentiated carcinoma is more atypical.

Case 30 Papillary carcinoma, oxyphilic cell variant

A whitish nodule is seen at the upper portion of
the left lobe (arrow).

papillary cluster
LBC

papillary cluster

LBC

LBC

multinucleatedgiant cell

Cytology: Papillary and sheet-like clusters are seen. The tumor cells show low N/C ratio, and thecytoplasm is abundant, densely-stained, and slightly granular. The cell border is distinct. The nuclei
are irregular shaped, and have intranuclear cytoplasmic inclusions.
Histology: The nuclei are consistent with papillary carcinoma, and the cytoplasm is eosinophilic.

Case 31 Papillary carcinoma, diffuse sclerosing variant
X-ray

frontal plane

The left lobe reveals numerous punctate echogenic foci without posterior acoustic shadowing(psammoma bodies). Grossly, the lesion occupies throughout the left lobe and isthmus.

LBC

LBC

mirror ball-like cluster

LBC

septate intracytoplasmic
vacuolesCytology: Numerous psammoma, lymphocytes bodies, mirror ball-like clusters, septate
intracytoplasmic vacuoles, and densely stained cytoplasm are characteristic of this variant.
Histology: Carcinoma cells are mainly present in the dilated lymph vessels. Carcinoma is
associated with squamous metaplasia and numerous psammoma bodies. Thyroid shows chronic
thyroiditis.

Case 32

Papillary carcinoma, cystic
frontal plane

proteinaceous materials

LBC

LBC

mirrorball-likecluster

Hobnail cells

irregular
shapednuclei
LBC

Cytology: Aspirated material is fluid, and exhibits low cellularity and proteinaceous background. LBC
smear is more cellular. Tumor cells appear as ball-like or mirror ball-like clusters, associated withhobnail cells. The cytoplasm tends to be abundant and weakly stained. Septate intracytoplasmic
vacuoles are seen. Chromatin pattern is not ground glass. Tumor cells showing sheet-like patternshow high N/C ratio, dense cytoplasm, irregular shaped nuclei, and prominent nucleoli.
Histology: Papillary carcinoma forms large cystic lesion that is not degenerative change.

Case 33

Papillary carcinoma, polycystic

micropapillary
growthpiling up

Polycystic lesions are present at the anterior of the left lobe. The findings ultrasonographically look
like benign nodules. Grossly, the lesions are sponge-like.
Histology: Multiple cystic papillary carcinoma lesions aggregate. Normal thyroid follicles lie
between the lesions. Papillary carcinoma shows micropapillary growth and piling up.

Case 34 Papillary carcinoma, fasciitis-like stroma
frontal plane
The cut surface ofthe tumor focallyshows whitish,translucent lesion
consistent with
fasciitis-like stroma.

vesselpapillary carcinoma

Histology: The stroma is composed of abundant collagenous connective tissue with plump
fibroblasts showing fascicular pattern. Small-sized blood vessels with thick wall are scattered.

Case 35 Papillary carcinoma withsquamous cell metaplasia

A infiltrative nodular lesion is seen in the rightlobe. The nodule is focally yellowish.

eddy formation

Cytology: In addition to conventional papillary carcinoma cells, cell clusters showing eddy
formation are seen.
Histology: Squamous eddies are present in the fibrotic stroma. They are not squamous cell
carcinoma, but metaplastic lesion.

Case 36

Papillary carcinoma (hobnail cell)

Subcutaneous nodule appeared 32 years after
papillary thyroid carcinoma was resected(needle tract implantation).

Hobnail cells

septateintracytoplasmic
vacuolesHobnail cells

Cytology: Hobnail cells and septate intracytoplasmic vacuoles are seen.
Histology: Papillary growth with hobnail pattern and septate intracytoplasmic vacuoles are seen.
Papillary carcinoma with prominent hobnail pattern is a moderately differentiated variant withaggressive clinical behavior.

Case 37

Poorly differentiated carcinoma

Whitish solid nodular lesion is present in theright lobe.

Cytology: Aspirated material is cellular. Tumor cells appear as large, solid cell clusters. There areno papillary or follicular clusters.
Histology: The tumor is composed of large atypical cells showing solid growth. The nuclei are
hyperchromatic and the cytoplasm is abundant. The cell border is distinct.

Case 38

Anaplastic carcinoma

The tumor occupies throughout the right lobe,
and shows necrosis and cystic degeneration.

papillary carcinoma

Cytology: In the background, tumor diathesis such as necrotic materials, neutrophils, and celldebris, is prominent. The carcinoma cells are apparently atypical.
Histology: The findings of cytological and histological section are not same, because the tumor was
resected after chemotherapy. The stroma exhibits lymphocytes, plasma cells, and foamy cells. The
carcinoma cells tend to be more atypical. Papillary carcinoma as pre-existing lesion is co-existent.

Case 39 Anaplastic carcinoma withosteoclast-like multinucleated giant cell

The trachea is compressed by a tumor mass and shifts
to the left.

LBC

LBC

LBC
PAX8

PAX8

Cytology: Carcinoma cells and osteoclast–like multinucleated giant cells are intermingled.
Elongated cytoplasm of the carcinoma cells is highlighted in LBC smear.
Histology (needle biopsy): Osteoclast-like multinucleated giant cells are conspicuous.
Immunostaining: Carcinoma cells are positive for PAX8.

Case 40

Medullary carcinoma (aggressive)

Medullary carcinoma tends to occur at theupper one third of the lobe.

vascularinvasion
calcitonin

MIB-1

Cytology: Carcinoma cells are discohesive and do not show sheet-like, follicular, or papillaryclusters. Chromatin pattern is salt & pepper. Nuclear grooves and intranuclear cytoplasmic
inclusions (arrow) are seen. No amyloid materials are seen.
Histology: Carcinoma cells proliferate as alveolar and solid patterns. This case shows marked
atypia, mitotic figures, vascular invasion, high MIB-1 labeling index; which are unusual findings inmedullary carcinoma, and indicate aggressive behavior.
Immunostaining: Calcitonin is positive.

Case 41

Medullary carcinoma (spindle cell)

Well-demarcated tumor is seen in the lower
portion of the lobe, where is not prevailing site.
LBC

entrappedfollicle

calcitonin

Cytology: Discohesive spindle cells aggregate without any specific arrangement. The cell shape islonger in LBC smear. The cytoplasm is weakly stained, and the cell border is indistinct. Chromatin
pattern is salt & pepper.
Histology: Carcinoma cells proliferate as solid pattern. Entrapped thyroid follicles should not be
confused to mixed medullary and follicular carcinoma component.
Immunostaining: Calcitonin is positive.

Case 42

Medullary carcinoma (pseudo-tubules)

A yellowish white, solid nodule is seen in theright lobe.
LBC

LBC

Chromogranin A

Cytology: Oval to short-spindled carcinoma cells are discohesive. The cytoplasm is weakly stained.
Chromatin pattern is salt & pepper. Elongated cytoplasm is highlighted in LBC smear.
Histology: Gland-like structure is visible. The structure is artifact caused by separation between
carcinoma cells, pooling of proteinaceous fluid, or intra-alveolar hemorrhage.

Case 43

MALT lymphoma
frontal plane

Multinodular lesions are seen in the backgroundof Hashimoto’s thyroiditis. Aspiration cytology was
performed for the nodule of the left lobe (arrow).
LBC

Flow cytometry using aspirated materials shows
restricted κ/λ light chain ratio (>5.0)
lymphoepithelial lesion

packing

packing
Cytology: Medium-sized lymphoid cells are predominant. Chromatin pattern is similar among
different-sized lymphoid cells. Irregular-shaped (elongated, spindled, and convoluted) nuclei areseen. In LBC smear, the nuclei are markedly degenerated (swelling, smashed chromatin pattern,
and discontinuous nuclear margin).
Histology: Packing and lymphoepithelial lesion are seen.

Case 44

Diffuse large B-cell lymphoma

Ultrasound examination reveals enlarged
and hypoechoic thyroid. Resected thyroid
tissue fragment is whitish.

cytokeratin
AE1/AE3

packing

packing
Cytology: Large-sized lymphoid cells are predominant. Non-neoplastic small sized lymphocytes andhistiocytes are also seen. The follicular cells are not typical oxyphilic cells.
Histology: Packing appearance is highlighted by cytokeratin AE1/AE3 immunostaining.

Case 45

ITET/CASTLE

CD5

Cytology: Aspirated materials are highly cellular. Carcinoma cells show solid three-dimensional
clusters. Lymphocytes and plasma cells are observed not only in the background, but also within
carcinoma cell clusters.
Histology: Carcinoma cells are round to oval and proliferate forming lobulated or anastomosing largesolid nests. The stroma is abundant and associated with an infiltration of lymphocytes and plasma
cells.
Immunostaining: CD5 is not always positive. CD5(-), PAX8(-), TTF-1(-), p63(+), cytokeratinAE1/AE3(+)

Case 46

Parathyroid cyst

Aspirated material is characteristic watery clear
fluid. Cytological examination is not useful becauseof no parathyroid cells in the fluid. A measurementof PTH level in the fluid is the most important tool.

Case 47 Parathyroid cyst and Parathyroid adenoma

Parathyroid cyst and adenoma are coincidentally present. This case is not parathyroid adenoma
with cystic degeneration. On color Doppler, parathyroid adenoma is suspected as a nodule withblood flow (arrow). Parathyroid adenoma is grossly yellowish brown (arrow).

Case 48

Parathyroid adenoma

A lobulated nodule is present at the posteriorside of the left lobe (arrow).

hemosiderin
hyalinization
Cytology: Aspiration cytology was performed because parathyroid tumor is not clinically suspected.
The smear is cellular. Tumor cells appear as overlapping trabecular pattern without colloid.
Chromatin pattern is coarse granular.
Histology: The nodule is composed of chief cells showing alveolar, trabecular, and solid growth. The
stroma is rich in capillaries. Satellite nodules, fibrosis, and hemosiderin-laden macrophages areprobably secondary to the preoperative aspiration procedure.