Histiocytic Sarcoma of Palatine Tonsil in a Pediatric Patient: A Case Report of a Rare and Aggressive Malignancy.

A 7-year-old boy with a history of recurrent tonsillitis presented with progressive left-sided throat pain, foreign body sensation, and cervical lymphadenopathy. During the examination, doctors found an ulcerated mass on the left palatine tonsil. A contrast-enhanced CT scan showed an enlarged tonsil that had uneven growth and narrowing of the opening. The tissue sample revealed large, abnormal cells with a lot of pinkish cytoplasm, irregular nuclei, and a high Ki-67 index (around 80%). Immunohistochemistry tests confirmed the cells were of histiocytic origin, strongly expressing CD68, CD163, LCA, and S100, confirming the diagnosis of histiocytic sarcoma. The boy had surgery to remove the affected tonsil and lymph nodes, followed by chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone. This case highlights a rare and unusual form of a serious blood cancer in a child. It also shows the diagnostic difficulties, as benign issues like recurrent tonsillitis can hide more serious problems. Making a correct diagnosis required a timely biopsy and suitable immunohistochemical tests. Given the tumor's high growth rate and risk of spreading early, treatment needed a team approach that involved complete local removal and immediate systemic therapy. Long-term follow-up is important, and more case reports and studies are necessary to determine the best treatment options and improve results in pediatric histiocytic sarcoma.