syphilis is a chronic systemic infectious disease caused by treponema pallidum , a microaerophilic spirochete , whose transmission occurs mainly by sexual contact . its course is characterized by a multistage evolution , in a total of 4 distinct clinical stages in cases of non - treated disease , in which symptomatic phases alternate with periods of latency . the myriad of possible clinical manifestations often represent a great challenge , a fact that led sir william osler to label it as  the great imitator. in this report , we present 2 cases in which the clinical manifestations of the patients initially simulated other dermatologic diseases , giving the impression of mucha - habermann disease ( pityriasis lichenoides et varioliformis acuta ) , in the first case and reiter 's syndrome ( reactive arthritis ) , in the second . male patient , 18 years old , white , single , student , born in and resident of rio de janeiro . he presented with a 1-month history of cutaneous lesions , jaundice , darkened urine and acholic stools . there was lesional polymorphism with lesions varying from erythematous papules and pustules to ulceronecrotic lesions with disseminated crusts on the face , trunk and limbs ( fig . 1 ) . physical examination revealed jaundice ( + + /4 + ) and bilateral inguinal lymphadenopathy . the exams showed positive serology for hepatitis b and alteration of the hepatic function tests . the initial impression of cutaneous vasculitis was not confirmed and clinical data , serologic tests and histologic findings led to the diagnosis of early malignant syphilis in an immunocompetent patient . male patient , 19 years old , single , student , born in and resident of rio de janeiro , presenting with conjunctival hyperemia and eyelid swelling on the right side for almost 2 years , which initially improved with steroid eye drops . later , there was progressive loss of visual acuity and onset of erythematous scaly lesions on the buttocks , palms and soles , besides erosions on the glans and inside the oral cavity ( fig . 3 ) . during the 6-month period preceding the medical consultation , arthralgia appeared on the knees , left sacroiliac articulation and elbows , accompanied by headache . the ophthalmological examination revealed panuveitis and the dermatological examination revealed keratoderma palmoplantaris , diffuse erythema on the trunk , scrotum erythema and erosion , circular residual violaceous erythema on the glans , anonychia and onychodystrophy , which hinted at the diagnosis of reactive arthritis . male patient , 18 years old , white , single , student , born in and resident of rio de janeiro . he presented with a 1-month history of cutaneous lesions , jaundice , darkened urine and acholic stools . there was lesional polymorphism with lesions varying from erythematous papules and pustules to ulceronecrotic lesions with disseminated crusts on the face , trunk and limbs ( fig . 1 ) . physical examination revealed jaundice ( + + /4 + ) and bilateral inguinal lymphadenopathy . the exams showed positive serology for hepatitis b and alteration of the hepatic function tests . the initial impression of cutaneous vasculitis was not confirmed and clinical data , serologic tests and histologic findings led to the diagnosis of early malignant syphilis in an immunocompetent patient . male patient , 19 years old , single , student , born in and resident of rio de janeiro , presenting with conjunctival hyperemia and eyelid swelling on the right side for almost 2 years , which initially improved with steroid eye drops . later , there was progressive loss of visual acuity and onset of erythematous scaly lesions on the buttocks , palms and soles , besides erosions on the glans and inside the oral cavity ( fig . 3 ) . during the 6-month period preceding the medical consultation , arthralgia appeared on the knees , left sacroiliac articulation and elbows , accompanied by headache . the ophthalmological examination revealed panuveitis and the dermatological examination revealed keratoderma palmoplantaris , diffuse erythema on the trunk , scrotum erythema and erosion , circular residual violaceous erythema on the glans , anonychia and onychodystrophy , which hinted at the diagnosis of reactive arthritis . syphilis is characterized not only for evolving in distinct clinical stages , but also for having the ability to mimic a wide variety of diseases , in each of its phases . in primary syphilis , localized erythema develops at the site of inoculation , which evolves into hardened and painless papules . classically , after the surface necrosis , the typical well - circumscribed ulceration develops , with hardened borders and clear base  the chancre  associated with regional adenopathy . primary syphilis , however , may present atypical morphology , location and symptoms , causing diagnostic difficulties , which results in only 3040% of patients being diagnosed in the primary stage . extragenital chancres can occur in any mucocutaneous surface exposed to the infection , but are more common in the oral cavity and anal region . any ulcerated nodular lesion associated to lymph adenopathy should lead to the suspicion of primary syphilis . differential diagnosis must be made with other infections , including tularemia ; cat - scratch disease ; sporotrichosis ; mycobacteriosis ; leishmaniasis and staphylococcal lymphangitis ; and with granulomatous diseases and neoplasms with nodal metastasis . in the anal region , it is rarely restricted only to a nodular hardening and can be accompanied by fissures , which leads to confusion with hemorrhoids , anal fissures or even neoplasms . features vary according to the number of inoculated spirochetes , concomitant use of antibiotics , presence of co - infections , and the patient 's immune state [ 1 , 4 ] . the secondary stage results from the hematogenous and lymphatic dissemination and multiplication of the microorganism in different tissues . these may be subtle , transient and pass unnoticed ; or so severe as to require hospitalization . however , over 90% of patients present rash , which is almost always characteristic . at the beginning , there is a macular rash with discrete pink , non - scaling , oval lesions  the syphilitic roseola  , predominantly on the trunk and upper flexor areas of limbs . then , the lesions may develop into a papular - macular , papular - desquamative , lenticular , corymbose , nodular , annular , follicular , pustular or impetiginous aspect . secondary syphilis polymorphism depends entirely on the intensity of the inflammatory infiltrate , level of cutaneous vascular involvement and the resulting ischemia . when papular lesions are pruritic and lichenoid , it may be difficult to differentiate from lichen planus . annular lesions may also resemble annular granuloma , pityriasis rosea and dermatophytosis . where there is a hyper keratotic component , the resulting lesions are indistinguishable from psoriasis [ 5 , 8 ] . hyperkeratotic plaques on the soles give the impression of calluses and , when desquamative , can mimic tinea pedis [ 1 , 5 ] . the differential diagnosis of nodular syphilis includes systemic mycosis , kaposi 's sarcoma , bacillary angiomatosis , foreign body granuloma type , lymphoma , pseudolymphoma , leprosy , sarcoidosis , and halogenoderma . secondary syphilis with pustular lesions can also lead to the erroneous diagnosis of pustular acne [ 8 , 9 ] . mucosal involvement can be part of the condition , consisting mainly of mucous patches , pharyngitis and condyloma lata . hair can be affected on the scalp , eyebrows and beard , and diffuse pattern alopecia increases the index of suspicion for the disease . the latter may be similar to alopecia areata , neoplastic alopecia , tinea capitis or trichotillomania . ungual disorders include fissures , beau lines , onycholysis , onychomadesis , onychogryphosis , nail pitting and others [ 1 , 6 ] . completing the picture , general symptoms may occur and rarely hepatitis , periostitis , arthritis , gastritis , meningitis and uveitis . in the second case reported here , the ocular and articular involvements associated with the mucocutaneous lesions led to a first diagnostic impression of reactive arthritis . this syndrome is characterized by the classical triad of arthritis , urethritis and conjunctivitis , after urethral or gastrointestinal infection . despite conjunctivitis being classically described in the syndrome , there are other associated ocular involvements , such as iritis and uveitis , the latter being diagnosed in our patient . that young man also presented , at the dermatological examination , keratoderma palmoplantaris and erosions on the glans , simulating , respectively , keratoderma blenorrhagica and circinate balanitis , and erosive lesions of the oral cavity . all these findings have been described in up to 20% of patients with reactive arthritis . a variant of secondary syphilis known as early malignant syphilis is characterized by a fast progression of papules , plaques , nodules , and polymorphic vesicular pustules with tendency to ulceration , covered with several layers of thick crusts , acquiring a rupioid aspect . however , at first glance , the acute onset and the exuberant features of the lesions led to the diagnostic hypothesis of pityriasis lichenoides et varioliformis acuta . also known as mucha - habermann disease , this disease is characterized by the appearance of generalized erythematous - purpuric papules that evolve with necrosis . finally , untreated syphilis evolves into a third form , very rare nowadays , with a variety of manifestations that occur months to years after the beginning of the infection . this stage is characterized by the presence of a small number of treponema , but with high cellular immune reactivity against this agent . microorganisms can invade different systems and lead to injury by a delayed type of hypersensitivity reaction . syphilis presents a highly variable clinical course and wide diversity of manifestations , which has made it known as the great mimicker . its ability to simulate various other diseases often causes its diagnosis to be a challenge . however , the lack of diagnosis of this quite prevalent disease can entail serious consequences for the patient . thus , it is of considerable importance that dermatologists and other specialists be familiarized with the many manifestations of syphilis and start considering it more often among their diagnostic hypotheses .
the authors present two cases of syphilis : one mimicking reactive arthritis and the other mucha - habermann disease . 
 both reports illustrate syphilis as  the great imitator , a description given by sir william osler , and call attention to the strong need for awareness among physicians of all specialties , especially the younger ones , who are not used to seeing this increasingly prevalent disease , as it once was in the past .