Atypical Presentation of Anaplastic Lymphoma Kinase–Positive Anaplastic Large T-Cell Lymphoma in a Young Patient With Intramuscular Nodules

Anaplastic lymphoma kinase–positive anaplastic large cell lymphoma (ALK+ ALCL) is a rare subtype of T-cell non-Hodgkin lymphoma. It commonly presents at advanced stages with B symptoms and lymphadenopathy. We present an atypical case of an 18-year-old man with progressively worsening bilateral thigh and gluteal pain associated with palpable nodules and intermittent low-grade fevers. An infectious and neoplastic work-up was conducted. After imaging and biopsy, ALK+ ALCL was diagnosed. This case highlights the difficulties and delay in diagnosing and treating ALK+ ALCL in a previously healthy young adult with unusual presentation.