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 60-year-old, otherwise healthy male patient presented with a painless swelling near the lower lid of his left eye at the ophthalmology clinic of Ohud hospital in Al-Madinah Al-Munawwarah, Kingdom of Saudi Arabia. At that time, he had had the swelling for almost 3 years. He had no similar swelling elsewhere in the body and no history of any malignancy in the past ().\nOn examination, the swelling was a superficial, non-tender, pink-colored nodule located horizontally on the tarsal plate of the left lower eyelid. It measured 2 cm x 1.5 cm x 1 cm and was mobile and firm in consistency. The swelling clinically resembled a benign lesion. The rest of the ocular examination was unremarkable in both eyes.\nThe excision biopsy of the lesion revealed a 2.5 cm x 1.5 cm x 1.3 cm mass. On the cut surface, a well-circumscribed, 2 cm x 1 cm x 0.8 cm grayish-white, firm tumor was seen in the center with 5millimeter (mm) surgical margins on all sides. A histological examination of the tumor showed overlying thinned-out epidermis, beneath which were seen sheets, cords and nodules of tumor cells lying in the pool of extracellular mucin (). At places, the cells showed cords, papillae and tubule formation, the tumor cells showed mild atypia and occasional mitotic figures; no necrosis was seen (), and all the surgical margins were free from the tumor. A diagnosis of mucinous adenocarcinoma was made. A wide range of immunohistochemistry panels were run to confirm the diagnosis. The tumor cells were strongly positive for cytokeratin 7 (CK7), cytokeratin 5/6 (CK5/6), tumor protein 63 (p63), estrogen receptor (ER), progesterone receptor (PR) and were negative for cytokeratin 20 (CK20) (). To investigate the possibility that this tumor did not represent a metastatic mucinous adenocarcinoma, the patient underwent a complete metastatic work-up which included, computed tomography (CT) of chest and abdomen, Positron emission tomography (PET) scan, esophago-gastro-duodenoscopy and sigmoidoscopy; no abnormalities were detected. The final diagnosis of a Primary mucinous adenocarcinoma of the eyelid was given.\nConsidering the age of the patient and the long duration and gradually increasing size of the swelling, the patient was scheduled for a wide local excision with free surgical margins and referred to the King Fahad Hospital in Al-Madinah Al-Munawwarah.\nFor the past year, the patient has been on a regular follow-up schedule and is clinically free from the disease at present.