Eruptive Collagenoma: Unmasking a Rare and Often Misdiagnosed Connective Tissue Nevus

Abstract Eruptive collagenoma is a rare, acquired connective tissue nevus characterized by the sudden appearance of multiple, asymptomatic, skin-colored papules or nodules composed predominantly of collagen. Here, we report two cases in an adult and adolescent male, who were otherwise healthy and who developed multiple, firm, papulonodular lesions on the body. Histopathological examination demonstrated thickened, disorganized collagen bundles with a relative reduction in elastic fibers on routine sections, confirming the diagnosis. Given the rarity of this condition, recognition is important to differentiate it from similar entities such as familial cutaneous collagenoma, papular elastorrhexis, and other connective tissue nevi. Eruptive collagenoma typically follows a benign, nonprogressive course with no systemic involvement. There is no definitive treatment; management is largely conservative, though surgical excision may be pursued for cosmetic concerns.