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- Presentation
Dermatology Case Series Highlighting Rare Diagnoses and Skin of Color Presentations
Description
This dermatology case series highlighted four uncommon or easily missed diagnoses, especially in skin of color. The first and most complex case involved an elderly man with acute hemorrhagic plaques, bullae, vesicles, necrotic eschars, GI bleeding, bacteremia, renal failure, and exposure to hydralazine and large iodine loads in the setting of CKD. Biopsy showed a neutrophilic dermatosis with cryptococcus-like vacuolated spaces, but stains and cultures were negative, supporting cryptococcoid neutrophilic dermatosis (CND), a rare reaction pattern associated with hydralazine, iodine, CKD, and other triggers; he improved on steroids and dialysis but later died from complications. The second case described a woman with lupus and subtle hyperpigmented, reticulated-appearing leg patches that were initially nonspecific on biopsy, but repeat deep biopsy revealed medium-vessel vasculitis consistent with cutaneous polyarteritis nodosa, emphasizing that in skin of color this can look like barely indurated pigmentary change and requires a low threshold for repeat biopsy. The third case showed a woman with acute diffuse scaling and pruritus after starting lamotrigine; biopsy and history supported a morbilliform drug eruption, illustrating that inflammatory drug rashes may present predominantly with scale rather than obvious erythema in darker skin. The final case involved slowly progressive facial hyperpigmentation with subtle hypertrichosis and a history of hand blisters, leading to diagnosis of porphyria cutanea tarda confirmed by elevated plasma porphyrins; she improved on hydroxychloroquine. Overall, the talk stressed careful morphology recognition, deep or repeat biopsies, and awareness of atypical presentations in skin of color.
View moreConclusions
- Cryptococcoid neutrophilic dermatosis appears to be a severe neutrophilic reaction pattern that can mimic cryptococcal infection histologically but is usually culture- and stain-negative for fungi.
- CND is most often associated with CKD plus iodine exposure and/or hydralazine use, with additional triggers including bacteremia, hematologic malignancy, and levamisole.
- The clinical pattern of CND is an acute hemorrhagic vesiculobullous eruption, often involving the face and upper extremities, and may be accompanied by systemic findings such as fever, GI bleeding, and pulmonary infiltrates.
- Laboratory clues to CND commonly include markedly elevated iodine levels, positive ANA, positive p-ANCA, and low complement levels, supporting an autoimmune/toxic neutrophilic process.
- Prompt recognition of CND matters because treatment with IV steroids, stopping hydralazine, and dialysis when iodine is elevated can improve outcomes, although reported mortality remains substantial.
- In patients with skin of color, medium-vessel vasculitis such as polyarteritis nodosa may present as subtle hyperpigmented or reticulated leg lesions with little obvious erythema or induration.
- Because these vasculitic lesions can be visually understated, clinicians should maintain a low threshold for deep biopsy and repeat biopsy when the first specimen is nondiagnostic.
- Morbilliform drug eruptions in skin of color may present predominantly with scaling rather than classic erythema, so acute diffuse scaling should still raise concern for a drug reaction.
- A careful medication history is essential in subtle eruptions, as lamotrigine and other new drugs can explain apparently nonspecific scaling rashes.
- Facial hyperpigmentation in skin of color should not be assumed to be benign pigmentary change, because porphyria cutanea tarda can present subtly and may be revealed by hypertrichosis and dorsal hand fragility or blistering.
- The initial screening test for porphyria cutanea tarda is a plasma total porphyrin level, and confirmation is supported by porphyrin fractionation.
- Porphyria cutanea tarda can be treated effectively with low-dose hydroxychloroquine or phlebotomy, and recognition of classic clues can lead to falling porphyrin levels and clinical improvement.
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