A 39-year-old Japanese male presented with a 3 months history of a skin tumor on the left side of the jaw. Past medical history revealed lung tuberculosis at age 20 years old. Physical examination showed a dome-shaped, slightly erythematous nodule measuring approximately 2 cm in diameter (Fig. ). Preoperative examination revealed no lymph node or distant metastasis. Punch biopsy was performed, and it was diagnosed as mucinous adenocarcinoma of the skin.\nThe tumor was excised with 5-mm surgical margin and was reconstructed with local rotational flap. The definitive histopathology showed small cellular nests of adenocarcinoma lying in pools of extracellular mucin that were separated by fibrocollagenous septae without involvement of underlying muscle. (Figure a,b) The immunohistochemical staining revealed that the tumor cells were positive for CK7, epithelioid membrane antigen (EMA), MUC1, MUC2, estrogen receptor (ER), and progesterone receptor (PR).\nThe patient again noticed a small tumor on the left side of the jaw in the area of the previous operation site 2 years after the primary operation. However, the patient had chosen not to be examined by a physician and left it alone for 4 years. Because of the rapid growth of the tumor, the patient visited our clinic. At this point, the tumor measured approximately 6 cm in diameter (Fig. a). Preoperative examination revealed invasion of the mandible and one left neck lymph node metastasis. The lesion was excised with at least 1-cm border of normal skin including the mandible (Fig. ). A left radical neck dissection was performed, and the mandible was reconstructed with a free scapula flap. The definitive pathology revealed MCS recurrence with no residual tumor cells in the excised normal skin area. One of 20 regional lymph nodes contained metastasis. Postoperatively, the patient was free of tumor and was followed up by the physician in charge every 3 months for 5 years and every 6 months for the next 5 years. The patient was disease-free for ten consecutive years on physical examination, chest X-ray, neck echogram, and ordinary blood test. Although the patient did not have any symptoms, the chest X-ray at the 11th year follow-up revealed multiple lung metastases (Fig. a,b). Additional chest computed tomography (CT), magnetic resonance imaging (MRI), and RI showed cervical vertebrate (Th5) tumor, and biopsy revealed metastasis of MCS. The patient received radiotherapy for pain control and died 3 year after the diagnosis of metastasis.
A 51-year-old male patient presented to the outpatient clinic with a painless nodule near the right lower eyelid. The mass had grown slowly over the past 3 years, and measured 0.9×0.7 cm during examination (). The lesion appeared benign in clinical examination, and under local anesthesia, the patient underwent a 3-mm-margin elliptical excision and primary closure. Histologic study of this first specimen revealed epithelial cell islands floating in a mucin lake, with the final diagnosis being mucinous carcinoma. The epithelial component showed a solid and cribriform growth pattern and the tumor cells revealed moderate nuclear atypia and a mitotic aspect. Additional immunostaining study revealed that the tumor cells were immunopositive for cytokeratins (CK)-7 and negative for CK-20 with 10% Ki-67 positivity in the active area (). We performed re-excision of the surgical site with an additional 3-mm margin, which was free of malignant histology. The possibility of a metastatic primary mucinous carcinoma (e.g., breast or gastrointestinal tract) could not be completely ruled out, but a systemic evaluation by positron emission tomography-computed tomography revealed no other suspected site of malignancy. During a close follow-up over 2 years, the patient did not experience any postoperative complication or recurrence ().