Misdiagnosis analysis and multidisciplinary collaborative treatment of primary cutaneous diffuse large B-cell lymphoma: case report.

Primary cutaneous diffuse large B-cell lymphoma (PC-DLBCL) is a rare subtype of non-Hodgkin lymphoma with nonspecific cutaneous manifestations, leading to frequent misdiagnosis. This case describes an elderly patient with severe ulcerative skin lesions who was misdiagnosed repeatedly and required multidisciplinary orthopedic-hematologic management, thus providing valuable evidence for clinical practice. An 85-year-old male presented with progressive erythematous papules, ulcers, and subcutaneous nodules on the right forearm, chest, back, and left upper arm. Pathology and immunohistochemistry confirmed primary cutaneous diffuse large B-cell lymphoma. He underwent orthopedic debridement, autologous skin grafting, and 4 cycles of R-miniCHOP immunochemotherapy. Skin lesions resolved completely without recurrence, and 7-month follow-up showed favorable recovery. The key take-away is that PC-DLBCL is often misdiagnosed; early pathological biopsy and multidisciplinary collaboration between orthopedics and hematology-oncology are essential for accurate diagnosis and effective treatment to improve prognosis in elderly patients.