Introduction
Gastric cancer is one of the most common malignancy, but reported cases of skeletal muscle metastases from gastric carcinoma are extremely rare. We report here a case of a 60-year-old female patient with skeletal muscle metastasis from advanced gastric cancer.
Case report
A 60-year-old woman presented with a right buttock pain for 2 months. She had been suffering from a pain in the right buttock area after she walked down from the 15th floor. Two years earlier, she was diagnosed with gastric cancer and had undergone total gastrectomy with lymph node dissection, splenectomy and colon segmental resection. The pathologic diagnosis was poorly differentiated adenocarcinoma with signet ring cell accompanied by lymph nodes but no any other distant organ metastases. She had undergone adjuvant chemotherapy with capecitabine and oxaliplatin. At follow-up, 1 year after surgery, a peritoneal metastasis was found and the patient received chemotherapy again. Her right buttock pain was aggravated by activities such like walking and squatting. On physical exam, she had tenderness at right buttock area and positive Patrick’s sign was observed. But, muscle weakness and sensory deficit were not observed. In laboratory test, white blood cell count was 5670 /mm³, percentage of segmented neutrophil was 74%, C-reactive protein was 0.38 mg/dL, creatine kinase was 41 IU/L, and lactate dehydrogenase was 177 IU/L. No bony abnormality was observed in X-ray. Under suspicion of gluteus muscle strain, oral analgesic was prescribed. As her right buttock pain had not subsided, we performed a comprehensive radiologic evaluation. In whole body bone scan, mild diffusely increased uptake was observed in right ilium (figure 1). Contrast-enhanced pelvic bone MRI revealed diffuse muscle swelling and high signal intensity change along both hip muscles in contrast enhanced T1 weighted image and peri-neural inflammation observed around the bilateral sciatic nerve in T2 weighted image. (figure 2). On PET-CT scan, right gluteus muscle swelling was observed but, FDG uptake (max SUV = 2.4 < 2.5) was not obviously increased in right buttock muscle (figure 3). To differential diagnosis of myositis, primary soft tissue sarcoma, and metastatic carcinoma, muscle biopsy was performed. Pathologic examination showed metastatic adenocarcinoma from stomach origin. The patient commenced on chemotherapy with paclitaxel and ramucirumab, the swelling and pain in right buttock are progressively improving.
Discussion
Skeletal muscle metastases reported to be approximately 0.8 - 16% in autopsy study and 1.2% in clinical study. The skeletal muscle metastases is challenging to diagnosis. The diagnosis of skeletal muscle metastases should be considered in the differential diagnosis of painful condition in advanced cancer patients. |
