Unusual Case of Solitary Perineal Subcutaneous Metastasis From Sigmoid Colon Cancer
A 49-year-old man presented for a solitary perineal subcutaneous metastasis without other organ involvement. He had undergone an anterior resection with curative intent for sigmoid colon cancer located at 25 cm from the anal verge 10 months earlier. The histopathologic report revealed a moderately-differentiated adenocarcinoma infiltrating the proper muscle, with involvement of 7 out of 16 lymph nodes. There was neither lymphovascular invasion nor perineural invasion. The pathologic stage was T2N2bM0, stage IIIB according to American Joint Committee on Cancer 6th edition. Postoperative course was uneventful without any complications. Adjuvant chemotherapy with the FOLFOX (fluorouracil, leucovorin, and oxaliplatin) regimen was recommended. However, he refused the regimen and preferred an oral chemotherapeutic regimen with capecitabine. The patient received 24 weeks of treatment with oral capecitabine, 1,250 mg/m2 twice daily, days 1.14 every 21 days. Approximately 3 months after completion of the oral chemotherapy, elevation of the serum careinoembryonal antigen (CEA) level was found upon routine postoperative follow-up. He had no complaints, but a subcutaneous mass about 4 cm in diameter was palpated in the posterior perineal area on rectal examination with perineal palpation. It was rubbery hard, well demarcated and mildly tender. The inguinal lymph node was not palpated, and there was no palpable mass on the trunk. Serum tumor markers were elevated; CEA, 14.1 ng/mL and carbohydrate antigen 19-9, 157 U/mL. Abdominopelvic computed tomography showed an ill-defined peripheral-enhancing low-attenuation mass, about 4.5 cm in maximal diameter, beneath the perineum (). The positron emission tomography-computed tomographic (PET-CT) scan showed a hypermetabolic focus in perineal subcutaneous fat (SUVmax 8.6), suggesting that the mass was malignant ().\nThe patient underwent a perineal resection and transverse loop colostomy. shows a solitary perineal subcutaneous metastasis from sigmoid colon cancer, which was confirmed as a metastatic adenocarcinoma upon histopathologic examination. Chemotherapy with the FOLFOX regimen was instituted. However, multiple lung metastases were detected on the PET-CT scan at 8 months after the perineal resection. The chemotherapy was switched to the FOLFIRI (fluorouracil, leucovorin, and irinotecan) regimen. The target agent was not affordable because of the patient's poor economic status. After the second cycle of FOLFIRI, some of the metastatic lesions had begun to progress, and new metastases had appeared at both the adrenal gland and the kidney. He visited the emergency department complaining of confused mental status, tremors and dyskinesia. A brain CT scan confirmed cerebellar metastasis. Whole brain radiotherapy was considered. The brain metastasis progressed rapidly, and he died 30 months after the diagnosis of perineal subcutaneous metastasis.