Dermatopathology Case Discussion: Spiroadenoma, Blastomycosis, and Necrolytic Erythemas

Conclusions

• Multiple spiradenomas/cylindromas are the same adnexal tumor spectrum and are recognized histologically by small basaloid cell islands with peripheral dark nuclei, central paler cells, lymphocytes, and hyaline basement-membrane droplets.
• Pustular and erosive skin lesions in the discussed differential are best approached by considering infectious, inflammatory, and toxic causes, with a mnemonic used to remember entities such as blastomycosis, chromomycosis, leishmaniasis, granuloma inguinale, halogenoderma, and pemphigus vegetans.
• Blastomycosis in tissue is suggested by its broad-based budding yeast with a thick asymmetrical refractile wall, often seen within pustules or giant cells and capable of mimicking other inflammatory eruptions.
• Necrolytic acral erythema should prompt evaluation for hepatitis C, especially because it can resemble nutritional deficiency–related necrolytic erythemas and often presents later in a more chronic, layered hyperkeratotic form.
• The necrolytic erythema group appears to represent a spectrum over time, with acute pallor, subacute erythema, and chronic hyperkeratosis rather than separate unrelated patterns.
• Acrodermatitis enteropathica, necrolytic acral erythema, and necrolytic migratory erythema share overlapping clinicopathologic features, so age, distribution, systemic symptoms, and associated disease are key to distinguishing them.
• Necrolytic migratory erythema is linked to glucagonoma syndrome, usually from a pancreatic APUD-cell tumor in the tail of the pancreas that secretes glucagon.
• In necrolytic migratory erythema, the eruption typically involves flexural, acral, and periorificial sites and can show vesicles, pustules, erosion, crusting, and a characteristic gyrate border.
• Recognizing the histologic stage of a lesion can help narrow the diagnosis, since the same disease may show acute pallor, subacute change, or chronic parakeratotic layering depending on timing.
• Overall, the presentation emphasizes that careful clinicopathologic correlation is essential because several uncommon dermatoses can look similar clinically but point to very different systemic diseases.