A metastatic histiocytic sarcoma case with primary involvement of the tonsil.

Histiocytic sarcoma (HS) is an extremely rare and aggressive hematopoietic tumor. Although it can be seen at any anatomic location, the most common primary sites are skin as extranodal region, locations including the lymph nodes and gastrointestinal tract. To the best of our knowledge, in light of PubMed search, this is the first primary tonsillar HS case presented with disseminated metastases at the time of diagnosis. A 58-year-old male patient applied with swelling on the right side of the neck, difficulty in swallowing, and weight loss. Positron emission tomography computed tomography was performed and increased pathological 18F fluorodeoxy D glucose uptake was detected in the right palatine tonsil, bilateral cervical multiple lymph nodes, liver masses, intra abdominal lymph nodes, and nodular lesion in the left adrenal gland. Tonsillectomy was performed and the pathological result was reported as HS. The patient did not respond to any treatment and had died after 5 months from the date of diagnosis. In conclusion, HS is generally diagnosed at advanced stage, it has limited chemotherapy response and high mortality rates. To understand this rare disease's pathophysiological and clinical features, further investigations are needed.