A 75-year-old man presented with recurrent pruritic eczema of the penis and scrotum that was refractory to medication of the local dermatologic clinic for one and a half years. The lesion consisted of an erythematous and indurated plaque with ulceration and exudation (). Review of the patient's history revealed that he underwent right hemicolectomy for adenocarcinoma in the ascending colon when he was 62 years old. He remained under regular follow-up for 13 years, during which no metastases were reported. Examination of skin biopsy from the inguinal folds revealed large cells with clear to eosinophilic cytoplasm that had infiltrated into the epidermis, singly and in clusters (). The initial histologic diagnosis of the skin biopsy was EMPD. The preoperative instrumental investigations showed no evidence of recurrence on the previous surgical site or other underlying internal malignancy. The patient underwent a mapping biopsy at multiple sites to accurately establish the boundary of the lesion, followed by wide excision and closure of the defect with a skin graft.\nThe resected perineum and penile shaft showed ill-defined indurated nodules with a firm consistency. The lesion in the overlying epidermis measured 6 cm, with a 1.5-cm-sized mass in the dermis. The cut surface was solid and gray-white with focal mucinous appearance. On histologic examination, the lowpower view showed a relatively well-defined mass occupying the dermis and subcutis (). The overlying epidermis showed irregular epidermal hyperplasia containing scattered large cells arranged singly or in groups, as in the previous skin biopsy, suggesting an epidermal pagetoid spread of underlying tumor cells (). The tumor showed two composite features in which solid nests of poorly differentiated carcinoma were juxtaposed with paucicellular mucinous lakes with floating tumor cell clusters (). The latter accounted for the majority of the tumor, about 70%, and the rest consisted of poorly differentiated components. Tumor cells in both the mucinous pool and more cellular area revealed the same histological features of abundant eosinophilic cytoplasm and large vesicular nuclei with frequent mitoses up to 7/10 high power field (, ). In situ lesions similar to ductal carcinoma in situ of the breast were also observed () with colonization of the hair follicles (). Overall histology suggested a mucinous carcinoma with minor poorly differentiated components.\nHistological differential diagnosis included PCMC and late metastasis of the previously diagnosed colon cancer. Histologic review of the patient’s previous colon cancer showed a 4.3-cm moderately differentiated adenocarcinoma with the assigned stage of T3N0M0. The tumor consisted of well-formed or cribriform patterns of tumor glands with frequently observed dirty necrosis (). There was no mucin production observed in the skin lesion.\nImmunohistochemical studies were performed. The Paget’s and dermal tumor cells of the skin lesion were positive for cytokeratin (CK) 7, CK20, gross cystic disease fluid protein-15 (GCDFP-15) (–), and carcinoembryonic antigen (CEA), but negative for caudal-related homeobox gene 2 (CDX-2). On the other hand, tumor cells of the colon cancer were positive for CK20, CDX-2, CEA, but not gross cystic disease fluid protein 15 or CK7. Additional staining of human epidermal growth factor receptor 2 and estrogen receptor (ER) was observed in the skin lesion (, ), but the lesion was negative for progesterone receptor (PR). Myoepithelial cells surrounding the carcinoma in situ were highlighted by CK5/6 immunostaining (). The overall immunohistochemical findings of the skin lesion were different from those of colon cancer but similar to those of breast cancer, but similar to those of breast cancer, indicating sweat gland origin. On the basis of these histologic and immunohistochemical findings, the two malignancies were considered to differ in origin, and the present case was a primary mucinous carcinoma of the skin.\nAnother challenge was to determine whether the minor poorly differentiated components were eccrine or apocrine in origin because there was no clear distinction in histologic and immunohistochemical features. We concluded apocrine differentiation of the lesion due to the location in the groin, where apocrine glands are many in number, and to the resemblance of apocrine carcinoma in the breast even though decapitation secretion was absent. In addition, close approximation and colonization of the hair follicle () favored the origin of the follicularapocrine unit.\nThe final pathologic diagnosis was PCMC with EMPD showing apocrine differentiation.\nThis case was approved by the institutional review board (IRB) of Kosin University Gospel Hospital, and informed consent was waived by the IRB (IRB reference number: 2017-10-010).
A 62-year old male presented to the oncology center for evaluation of a painless, superficial nodular lesion over his left lower eyelid that had slowly grown over the course of approximately 18 months, to measure 4.0 × 2.0 cm. Patient gave history of a similar swelling at the same site which had appeared in July 2005 and after a similar slow, painless progressive increase in size, it had been excised in February 2006. The histopathology report from the previous surgery was not available for review. The swelling recurred within six months and displayed a painless, gradual, progressive increase in size till he presented at our center. On examination, he had a well-defined, irregularly marginated nodular lesion over the left lower eyelid []. The overlying skin was normal in appearance and freely mobile over the underlying nodular lesion except for an area of 1 × 1 cm at the lateral end, where the scar of the previous surgery was tethered to the mass. There was no regional lymphadenopathy. The lesion appeared free from the underlying orbital ridge. Fine needle aspiration cytology from this lesion reported a benign adenexal tumor. The lesion was excised with 5 mm margins under general anesthesia. The resultant defect involved the entire lower eyelid and was reconstructed by a Mustarde's cheek rotation flap. This was a large skin flap which was rotated from the cheek. Incision began at the lateral canthal angle, extending upward onto the temple, and swinging posteriorly just anterior to the ear and then inferiorly across the mandible []. Eight weeks postoperatively, there was marginal ectropion and lateral tissue sag []. Gross pathology revealed a subcutaneous nodule of tan, gelatinous tissue measuring 4 × 2 × 1.0 cm. Microscopic examination revealed a dermal tumor composed of epithelial cell islands surrounded by lakes of mucin consistent with the diagnosis of mucinous carcinoma []. The lateral margins were tumor cell-free but the deep resected margin was involved. A thorough search for other possible sources of mucinous adenocarcinoma was made. Upper and lower gastrointestinal study, contrast enhanced computer tomography study of the chest and abdomen, as well as a whole body Positron Emission Tomography scan were negative for any other primary.