A Case of Sotos Syndrome With Right Shoulder Disarticulation Due to a High-Grade Malignant Peripheral Nerve Sheath Tumor in the Right Arm and Shoulder.

Sotos syndrome is an autosomal dominant genetic disorder that causes an overgrowth of the body characterized by distinctive craniofacial features, excessive growth, and neurodevelopmental delay. We present a 49-year-old man diagnosed with Sotos syndrome and with a previous history of lymphoma in remission who developed a high-grade malignant peripheral nerve sheath tumor (MPNST) affecting the right upper extremity. Due to the tumor recurrence of a high-grade malignant peripheral nerve sheath tumor (MPNST) in the right arm and shoulder, the patient underwent a right shoulder disarticulation. This aggressive clinical course was further complicated by a pathological fracture, persistent local neoplastic disease, and the eventual development of pulmonary lesions radiographically highly suggestive of metastatic disease, though tissue biopsy was not performed. The patient originally refused amputation despite advice for early definitive surgical therapy, which caused the condition to worsen. Palliative radiation therapy, multi-agent chemotherapy, and supportive care for pain and psychological distress were part of the subsequent management. This case underscores the aggressive clinical course and the importance of early diagnosis, prompt surgical intervention, multidisciplinary care, and effective patient counseling.