Hyperkeratotic plaques resembling an oyster shell.

History

A 34-year-old man with acquired immunodeficiency syndrome (AIDS) presented with 2 years of pruritic, slowly growing lesions after discontinuation of all antiviral medications. On examination, he had a cobblestoned, dark brown plaque on the perioral cutaneous and mucosal lip (Fig 1) and 2 large annular brown plaques with heaped-up mounds of scale and violaceous rims on the right shin and posterior thigh (Fig 2) with a smaller similar lesion on the scrotum. A skin biopsy of the perioral and right thigh plaques found a lichenoid infiltrate with numerous plasma cells (Fig 3). An immunostain is shown in Fig 4.

Fig 1

Fig 2

Fig 3

Fig 4

Question 1: What is the diagnosis?

Psoriasis

Majocchi granuloma

Rupioid syphilis

Hypertrophic lichen planus

Lobomycosis

Answers:

Psoriasis – Incorrect. Although psoriasis can have a rupioid morphology, the presence of spirochetes on immunostains supported an infectious diagnosis.

Majocchi granuloma – Incorrect. Majocchi granuloma is a deep folliculitis caused by a cutaneous dermatophyte infection. Skin scraping in this case had no growth in dermatophyte test media, and tissue cultures were negative for bacteria, fungus, and atypical mycobacteria.

Rupioid syphilis – Correct. This patient's rapid plasma reagin was reactive with a titer of 1:512, and his Treponema pallidum hemagglutination assay was positive. Rupioid syphilis is characterized by well-demarcated hyperkeratotic scaly plaques with a thick, adherent crust that resembles the back of an oyster shell.

Hypertrophic lichen planus – Incorrect. The presence of spirochetes on immunostains supported an infectious diagnosis.

Lobomycosis – Incorrect. Lobomycosis is a chronic fungal infection presenting with keloidal-like plaques. Round yeast-like structures were not seen on histology.

Question 2: Which of the following disease subtypes does this case best represent?

Congenital

Primary

Secondary

Tertiary

Endemic

Answers:

Congenital – Incorrect. Congenital syphilis is usually the result of transplacental infection of the fetus from an infected mother and has varied clinical manifestations including prematurity, rhinorrhea, and mucocutaneous lesions (in early congenital syphilis) and interstitial keratitis, neurosyphilis, bone disease, and cardiovascular disease (in late congenital syphilis).

Primary – Incorrect. The chancre, an indurated painless ulcer, is the initial lesion of syphilis and appears about 21 days after exposure.

Secondary – Correct. This patient has late latent secondary syphilis. Lesions of secondary syphilis are protean in clinical presentation and histology and have easily identified organisms with immunostain, as seen in our patient. The distinction between early and late latent secondary syphilis is based on whether the primary infection occurred within the past 12 months.

Tertiary – Incorrect. Cutaneous manifestations of late latent secondary and tertiary syphilis are notably different. Tertiary syphilis typically presents with granulomatous lesions without identifiable spirochetes on biopsy.

Endemic – Incorrect. Endemic syphilis is a form of nonvenereal syphilis and clinically presents with lesions in the oral and nasopharyngeal mucosa.

Question 3: The clinical morphology seen in this case has been reported in all of the following EXCEPT:

Psoriasis

Reactive arthritis

Scabies

Histoplasmosis

Dermatomyositis

Answers:

Psoriasis – Incorrect. Rupioid lesions have been reported in psoriasis.

Reactive arthritis – Incorrect. Rupioid lesions have been reported in reactive arthritis.

Scabies – Incorrect. Rupioid lesions have been reported in keratotic scabies.

Histoplasmosis – Incorrect. Rupioid lesions have been reported in disseminated histoplasmosis.

Dermatomyositis – Correct. Rupioid morphology has been described in association with all of the other answer choices including psoriasis, reactive arthritis, keratotic scabies, and disseminated histoplasmosis. Rupioid lesions of syphilis are most commonly seen in patients with varied degrees of immunosuppression including HIV, malnutrition, diabetes, or pregnancy.