Granulomatous diseases

• Asymptomatic, benign and self-limited granulomatous disease of the dermis seen in both adults and children
• Unknown etiology; may include trauma and sun exposure
• Presents as skin-colored to pink non-scaly papules coalescing into annular or arciform plaques, typically over dorsal hand or foot; variants listed below:



GA Variant Description   Patch GA (Macular) Patches of erythema typically over extremities ± trunk   Generalized GA (Disseminated) Flesh-colored pink papules over trunk/extremities; poor response to treatment; association with diabetes   Perforating GA Small papules with central umbilication and crusting (discharging necrotic collagen) typically over dorsal hands   Subcutaneous GA Deep dermal nodules similar to rheumatoid nodules; typically asymptomatic



• Histology: necrobiotic foci in dermis surrounded by histiocytes (palisading granulomas) or histiocytes splayed between collagen bundles (interstitial type), mucin accumulation, ± perivascular lymphocytes/eosinophils
• Treatment: clinical observation as typically self-limited (50–75% of cases with resolution in 2 years) in localized GA, potent topical corticosteroid or intralesional corticosteroid

Figure 3.14 A: Granuloma annulare B: Granuloma annulare (Courtesy of Dr. Paul Getz) C: Subcutaneous GA (Courtesy of Dr. Paul Getz)

Figure 3.15 A: Necrobiosis lipoidica (Courtesy of Dr. Sophie M. Worobec) B: Necrobiosis lipoidica (Courtesy of Dr. Paul Getz) C: Necrobiotic xanthogranuloma (Reprint from Morgan MB, Smoller BR, Somach SC. Deadly Dermatologic Diseases. New York, NY: Springer; 2007)