Familial Reactive Perforating Collagenosis: Clinical, Dermoscopy, and Histopathological Features in Two Siblings

Transepidermal elimination disorders include reactive perforating collagenosis (RPC), perforating folliculitis, elastosis perforans serpiginosa, and Kyrle's disease. RPC is a rare transepidermal elimination disorder wherein altered collagen is extruded through the epidermis. It has two types: rare inherited form and relatively common acquired form. Most inherited cases present during infancy or early childhood with papules on extensor surface of hands, elbows, knees preceded by superficial trauma. We report two female siblings of 11 and 10 years with multiple, symmetrically distributed, hyperpigmented papules with central keratotic plug, predominantly over extensor aspects of extremities with no aggravating and relieving factors. Clinical diagnosis of familial RPC was confirmed by consistent dermoscopic and histopathological findings. Both children were started on oral isotretinoin 10 mg/day with topical 12 ammonium lactate. Keywords: Inherited, reactive perforating collagenosis, transepidermal elimination disorders