Temporal bone mass as the initial presentation of peripheral T-cell lymphoma in an infant: a case report

Peripheral T-cell lymphoma (PTCL) is an exceptionally rare diagnosis in infants, particularly under one year of age. The exceptional nature of the case in patients under one year of age and the limited cancer-specific treatment protocols pose significant diagnostic and therapeutic challenges. We report the case of an 11‑month‑old male infant presenting with a rapidly enlarging right temporozygomatic mass that developed over a two‑month period, accompanied by ipsilateral exophthalmos and B symptoms, specifically weight loss. Physical examination demonstrated marked facial asymmetry, ptosis, exophthalmos, a secondary parieto‑occipital lesion, and ipsilateral submandibular lymphadenopathy. Imaging studies demonstrated multiple infiltrative lesions characterized by lytic involvement of bone and extension into the central nervous system. The initial differential diagnosis encompassed fibrous dysplasia, Langerhans cell histiocytosis, neuroblastoma. Morphological evaluation and immunohistochemistry confirmed a diagnosis of mature peripheral T-cell lymphoma. The patient was treated with bridging chemotherapy (carboplatin and etoposide), followed by six cycles of CHOP protocol, and subsequently underwent autologous hematopoietic progenitor cell transplantation. He achieved complete remission and remains disease-free at the time of publication. This case highlights the diagnostic complexity of PTCL in infants, where clinical features can mimic more common pediatric conditions. The lack of standardized pediatric treatment protocols necessitates the extrapolation of adult regimens, which may not account for pediatric pharmacodynamics. Despite these limitations, the patient responded favorably to the tailored therapy, underscoring the importance of early morphological and immunohistochemical diagnosis and multidisciplinary management. Peripheral T-cell lymphoma should be considered in the differential diagnosis of aggressive soft tissue masses in infants. Morphological evaluation and immunohistochemistry is essential for accurate diagnosis, and adult-based treatment protocols may offer effective outcomes when tailored to pediatric needs.