A 44-year-old female was diagnosed with follicular lymphoma (FL), grade 3A stage III, by right cervical lymph node biopsy at the age of 43 years. The patient chose to not receive the treatment despite the high tumor burden. The patient came back after 18 months with respiratory distress and had systemic infiltration and pleural effusion. Positron emission tomography (PET)/computed tomography (CT) showed fluorine-18 deoxyglucose accumulation with maximum standardized uptake value ranging from 10 to 18 in bone marrow, liver, spleen, lung, and systemic lymph nodes (cervical, supraclavicular, infraclavicular, axillary, mediastinal, hilar, para-aortic, iliac, and inguinal). Left inguinal lymph node biopsy revealed mixed cellularity classical Hodgkin lymphoma (CHL), which was thought to be an FL transformation or a composite condition. The patient was treated with A + AVD and achieved lymph node shrinkage as well as improvement of tumor fever and pleural effusion. Interim PET/CT showed improvement in most parts after two courses; however, it revealed some new or progressive lesions in the bone marrow and left cervical lymph nodes. Left cervical lymph node biopsy revealed nodular sclerosis CHL. The patient was treated with ESHAP, which resulted in stable disease; following this, the patient was treated with nivolumab, which was highly effective. FL transformation to CHL is rare, and this is the first report of such transformation without treatment.
Keywords: Classical Hodgkin lymphoma; Follicular lymphoma; Histological transformation; Nivolumab.