Primary Extranodal Nodular Lymphocyte-Predominant Hodgkin Lymphoma of the Cubital Fossa: A Case Report.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare B-cell lymphoma that typically presents as localized nodal disease. Primary extranodal involvement, particularly within soft tissue, is exceedingly uncommon and poses diagnostic and management challenges. We report a 25-year-old male who presented with a painless subcutaneous mass in the left cubital fossa. Core biopsy suggested a B-cell lymphoma with a differential diagnosis of NLPHL versus T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL). Comprehensive staging, including bone marrow biopsy and PET-CT, demonstrated isolated disease without nodal or visceral involvement. Wide local excision revealed classical morphologic and immunophenotypic features of NLPHL, including nodular architecture, preserved follicular dendritic cell meshworks, and LP cells expressing CD20 and B-cell transcription factors, confirming Stage IA disease. Following multidisciplinary discussion, the patient was managed with active surveillance after complete surgical excision, given the localized, asymptomatic presentation and low tumor burden. At the most recent follow-up, nine months after complete excision, the patient remained disease-free, with no clinical or laboratory evidence of recurrence. This case highlights an exceptionally rare presentation of primary extranodal NLPHL in soft tissue of the cubital fossa. It underscores the critical role of excisional biopsy in distinguishing NLPHL from THRLBCL and supports active surveillance as a feasible management strategy in carefully selected patients with completely resected Stage IA disease.