Diffuse large B cell lуmphoma (DLBСԼ) is the most common histologic subtype of non-Hodgkin lуmphοma (NНԼ) accounting for approximately 25 percent of ΝНԼ cases. Additionally, Diffuse Large B Cell Lymphoma is the most common lymphoma. In the United States and England, the incidence of DLΒCL is approximately 7 cases per 100,000 persons per year. In Europe as a whole, the incidence is approximately 4.92 cases per 100,000 persons per year. Like most other NHLs, there is a male predominance with approximately 55 percent of cases occurring in men. Incidence increases with age; the median age at presentation is 64 years for patients as a whole.

IB, 45 years male patient. MRI scan taken in 2022 after a complaint of pain in right knee revealed a malignant tumoral lesion (osteosarcoma?) that caused intramuscular invasion in a segment of approximately 20 cm in the 1/2 distal femur and caused extensive cortical destruction in the distal. A biopsy was taken from the distal right femur. He was diagnosed with non-Hodgkin lymphoma and diffuse large B-cell lymphoma. Bcl-2, Bcl-6 and c-myc were found to be negative. After 4 cycles of R-CHOP protocol, PET-CT revealed minimal progression in the left clavicle and the IPI score was high. The patient' s R-CHOP treatment was completed for 6 cycles with 2 cycles of intrathecal MTX. Afterwards, 2 cycles of maintenance rituximab were given. The patient, who subsequently went into remission, was followed up.

This case shows us that NHL cases may present in a location such as primary bone tumor. The possibility of lymphoma should be considered in patients with atypical localization.