Bone marrow involvement as the initial presentation of hodgkin's lymphoma is undetectable by18F-fluorodeoxyglucose positron emission tomography/computed tomography

We report a 28-year-old male who presented with fever and bone pain without peripheral lymphadenopathy observed during initial physical examination. Subsequent bone marrow examination revealed the presence of Reed-Sternberg (RS) cells, which led to a diagnosis of mixed cellularity subtype of Hodgkin's lymphoma (HL). However, the initial ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan did not show any detectable marrow or nodal lesions, with the exception of FDG uptake in an extranodal lesion over the right adrenal gland. Two weeks later, a 2-cm enlarged lymph node over the left submandibular region appeared. Excisional biopsy revealed HL. Mixed cellularity subtype of stage IV HL with initial bone marrow and unilateral adrenal gland involvement followed by submandibular lymphadenopathy was diagnosed, according to clinical, imaging, and histological manifestations. This patient received six cycles of chemotherapy with regimen of doxorubincin, bleomycin, vinblastine, and decabazine (ABVD). The subsequent FDG-PET/CT scan revealed complete remission after chemotherapy.