Type 2 diabetes mellitus complicated by acquired reactive perforating collagenosis

Rationale: Acquired reactive perforating collagenosis (ARPC) is a perforating skin disorder characterized by transepidermal elimination of degenerated collagen. It is often associated with systemic diseases, such as diabetes and chronic kidney disease. Due to its diverse clinical manifestations, ARPC is often misdiagnosed or overlooked in clinical practice. Patient concerns: A 66-year-old female with a 22-year history of type 2 diabetes (T2DM) was admitted to the hospital due to poor blood glucose control. She had been experiencing itching and a rash for nearly 3 months and had previously been treated at another hospital, but the response was unsatisfactory. Physical examination revealed erythema, papules, and nodules on the extensor surfaces of both lower extremities. Diagnoses: The patient had a confirmed diagnosis of T2DM. Histopathological examination of the skin lesion revealed collagen fibers penetrating through the epidermis, which were positive for Van Gieson staining. Therefore, the final diagnosis was T2DM complicated by ARPC. Interventions: Oral antihistamines and topical corticosteroid cream were given along with blood glucose control. Outcomes: After the aforementioned treatment, the patient’s blood glucose level was well controlled, the skin lesions gradually healed, and the pruritus significantly subsided. Lessons: This case suggests that the occurrence of ARPC may be closely related to persistent hyperglycemia. ARPC skin lesions can be regarded as one of the cutaneous manifestations of underlying metabolic diseases. When such lesions appear or worsen, clinicians should comprehensively evaluate the patient’s overall condition, particularly blood glucose control. Treatment requires a dual-pronged approach, including active correction of systemic triggers such as hyperglycemia, as well as local intervention for skin lesions.