Delayed diagnosis of a primary Diffuse Large B-Cell Lymphoma (DLBCL) of the humeral head, presenting as pathological fracture: A case report and review of the literature.

Primary bone lymphoma (PBL) is a malignant lymphoid neoplasm affecting a solitary bone or multiple skeletal sites without visceral or nodal involvement. Diffuse large B-cell lymphoma (DLBCL) is the most common histologic subtype, accounting for up to 80% of cases. We report a case of a misdiagnosed DLBCL, in a 52 years-old male patient, presented to our department with acute pain, permeative blastic-sclerotic mass in his left humeral head, but non-diagnostic fine-needle biopsy. Due to his clinical improvement with conservative means, he skipped biopsy repetition, presented three years later with pathological fracture of the humeral head. An open biopsy and histological examination revealed a DLBCL of the germinal center B-cell-like (GCB) subtype. After appropriate staging, he received chemo-immunotherapy with 8 cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP) and adjuvant radiotherapy, with complete remission after 65 months of follow-up. A year later, due to severe shoulder impairment, he underwent surgical excision of the upper part of the humerus and reconstruction with a reverse mega-prosthesis having an excellent functional recovery. Two years later, he demonstrated loosening, osteolysis and excursion of the stem through the lateral humeral cortex; a revision operation was performed with a good final outcome at two years follow-up. A systematic review of PLBs in the shoulder is provided as well, showing that patients usually present with chronic pain, palpable mass or pathological fractures. MRI and PET-CT are important for initial diagnosis, but this must be established with bone biopsy and immunocytochemical studies. Chemotherapy and radiotherapy can provide complete regression in the majority of the patients; surgical treatment is used in neglected cases and when there is severe functional impairment.