A case report: an 11-year-old boy with peripheral T-cell lymphoma presenting after a five-year indolent inguinal lymphadenopathy

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is defined by the World Health Organization as a mature post-thymic T-cell neoplasm diagnosed only after the specific entities have been excluded. It is rare in children, accounts for a small minority of pediatric non-Hodgkin lymphoma, has no established standard of care, and is characterised as clinically aggressive with advanced-stage presentation over weeks to months. Herein, we present an 11-year-old Ethiopian boy presented with a solitary, painless right inguinal swelling that had been present and clinically stable for five years enlarging rapidly over three months. He had no B symptoms, no tuberculosis contact and no known immunodeficiency. A 16-marker immunohistochemical panel showed the lesional intermediate-sized cells to be CD3 + and CD5 + with mutant-type p53 expression and only scattered residual CD20+/PAX-5 + B-cell aggregates; CD30, CD15, CD23, BCL-6, CD10, CD1a, CD8, CD99 and TdT were negative, the follicular dendritic cell meshwork was absent, and the Ki-67 index was 30–35%, establishing PTCL-NOS. Staging demonstrated bilateral cervical adenopathy, extensive confluent abdominopelvic nodal masses with a necrotic right inguinal node, and multiple bilateral pulmonary nodules, giving Ann Arbor stage IV disease. Bone marrow and cerebrospinal fluid were uninvolved and lactate dehydrogenase was persistently normal. He was treated with an ALCL chemotherapy regimen through the B3 course and showed improvement.