Metastatic malignancies of the hand are rare and metastases to the skeletal muscle from the gastrointestinal system are even much rare. Here we present a case of metastatic ileocecal adenocarcinoma to the thenar muscle, which is the first report of thenar muscle metastasis from ileocecal adenocarcinoma with P53 mutation. To date, only two other cases of thenar muscle metastasis have been documented, one is from squamous cell carcinoma of the lung and the other is from rectal carcinoma. The present 67-year-old Chinese man of poorly differentiated adenocarcinoma of the ileocecal region developed metastatic carcinoma in the right thenar eminence, which presented with swelling and pain. Magnetic resonance imaging of the right hand revealed a well-defined enhanced mass in the right thenar muscle. It was proved to be metastatic adenocarcinoma using core needle biopsy, which was supported to be gastrointestinal origination by positive immunoreaction with CDX2. Positive immunoreaction with P53 protein indicated the poor prognosis of the patient. Further systemic evaluation including computerized tomography scans revealed extensive metastases to liver, right kidney, right abdominal wall, left axillary and right subclavicular lymph nodes, and skin of the right thigh. Treatment was given with palliative systemic chemotherapy. After 8 cycles of chemotherapy, the swelling and pain of the right thenar were ameliorated, and the patient regained full use of his right hand and his quality of life was improved. The patient died of liver metastasis 9 months after the diagnosis of the right thenar metastasis. In conclusion, here we display a case of thenar skeletal muscle metastasis from P53 mutated ileocecal adenocarcinoma, who survived 9 months after diagnosis of the rare metastasis. If an oncological patient presents an intramuscular mass, muscle metastasis must be included in the differential diagnosis. Metastatic hand tumors generally indicate systemic spread, so the treatment is usually palliative and the prognosis is poor. The primary objective of treatment is improvement of the patient's quality of life.
Keywords: Ileocecal adenocarcinoma; metastasis; thenar muscle.