A sarcomatoid malignancy originating in the right cervical lymph nodes with atypical pathological characteristics: a case report of an incidental finding.

Background: Primary malignancies of the cervical lymph nodes with special pathological characteristics are relatively uncommon in clinical settings, and there have been few reports on these tumors. The precise basis for their pathogenesis is poorly understood, and their diagnosis can be challenging. In addition, no clinically validated treatments have been established to date for affected patients. Case Description: Here, we describe a case of a 65-year-old male patient who exhibited the enlargement of several lateral and supraclavicular lymph nodes on the right side of his neck that presented as a large mass associated with a high fever and benign leukocytosis. He did not exhibit any relevant prior history. Radiological assessment revealed that this lesion was the primary tumor and that it has since spread to the liver. Histological assessment was unable to definitively classify the pathological characteristics of this tumor. Without any relevant morphological findings, immunohistochemical outcomes were not sufficiently specific to clarify the origin of these cells. When distinguishing it from similar sarcomas of the lymphohematopoietic system, it was found to not be typical of a histiocytic or dendritic cell tumor. Treatment to this patient was performed following multidisciplinary consultation and consisted of one course of a cyclophosphamide plus doxorubicin, vincristine, and dexamethasone regimen and two courses of the cyclophosphamide plus pirarubicin, vincristine, and dexamethasone regimen. However, the tumor exhibited minimal response to such treatment. While radiotherapy was proposed, the patient lacked confidence in the approach and declined treatment. He eventually developed severe tumor-associated complications. In the discussion section of this report, we detail and analyze the pathogenesis, diagnosis, and referential treatments of this rare malignancy. Conclusions: This is the first report describing such a malignancy, and we hope that the publication of these findings can lead to the recognition of this tumor while supporting efforts to acquire greater experience in the diagnosis and treatment of affected patients.