Acquired reactive perforating collagenosis associated with diabetes mellitus and renal insufficiency

History: A 60-year-old man with diabetes mellitus and chronic renal insufficiency needing hemodialysis was admitted with a 3 months history of multiple hyperkeratotic papules on the trunk and extremities partly ulcerated with a keratotic central plug. Investigations: Laboratory tests revealed elevated levels of blood urea nitrogen, creatinine, and HbA(1c). Histopathology showed vertical strands of collagen perforating from the ulcerated lesions. Course, diagnosis and treatment: The biopsy specimen was consistent with acquired reactive perforating collagenosis. The progression was stopped and secondary wound healing was initiated after two weeks of therapy with allopurinol and PUVA. Conclusion: Acquired reactive perforating collagenosis should be considered when ulcera with oystershell-like keratotic plugs are found especially in patients with predisposing diseases like diabetes and renal insufficiency. A good interdisciplinary cooperation between internist and dermatologist is crucial for the early recognition by histopathology and the immediate treatment.