Diffuse Large B-Cell Lymphoma Presenting as a Thigh Mass: A Case Report.

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma and typically occurs later in life. Classic symptoms include lymphadenopathy, fevers, night sweats, and weight loss. Extranodal presentations are uncommon and may mimic other malignant processes. A 76-year-old female presented with right thigh swelling and pain. Imaging demonstrated a soft-tissue mass with radiologic features concerning for sarcoma. A biopsy was performed, and histopathology confirmed DLBCL. Primary involvement of the thigh by B-cell lymphoma is exceedingly rare and may be confused with sarcoma due to its clinical and radiographic appearance. Clinicians should be aware of this potential extranodal presentation of DLBCL. This case underscored the importance of maintaining a broad differential diagnosis in the evaluation of extremity masses, including lymphoma.