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).
The patient was a 62-year-old female of African American ethnicity, with a past medical history of type 2 diabetes mellitus, chronic kidney disease secondary to diabetes, glaucoma, macrocytic anemia, chronic back pain and hypertension, who initially presented to her ophthalmologist with a small growth over her left upper eyelid. The patient had the swelling for more than four years that had gradually increased in size. She did not have it evaluated as it very occasionally caused symptoms like on and off tearing, itching, and irritation. She decided to seek medical care when she noticed some tenderness over the lesion. On initial evaluation, she was noted to have a 0.6 mm, elevated, cystic-appearing subcutaneous nodule in the central medial left upper lid margin and lash row. It was noninflamed and tender to palpation. The lesion was in close proximity to the cornea. All other eyelid and orbital functions were normal.\nThe lesion was initially thought to be a benign cyst. As it was symptomatic, it was excised and reconstruction was done. Histopathological analysis revealed positivity for carcinoma cells and suggested that it was a mucinous colloid carcinoma. As the margins were positive, a repeat excision with wider margins and reconstruction via advancement of her lateral full thickness upper lip into the central upper lid was done following a superior cantholysis of the lateral canthal tendon. The surgeons felt that there was no evidence of regional extension beyond what was excised. This was further confirmed by CT imaging of the orbits that revealed no locoregional extension or residual tumor (Figure ). Histopathological exam showed that the tumor was present within the dermis abutting the orbicularis muscle and was composed of lobules of epithelial cells floating in pools of mucin. Small ductal structures were observed within the lobules. A dual population of epithelial cells was identified with mild to moderate pleomorphism admixed with some atypical mitotic figures. Adjacent to the tumor, there were distended ductal structures with atypical proliferation of epithelial cells with a cribriform architecture and extracellular mucin. The tumor extended into the deep tissue edges, but perineural invasion was not identified. Immunohistochemical analysis revealed that the tumor was positive for tumor protein p63 (P63) and cytokeratin 7 (CK7) and negative for cytokeratin 20 (CK20), thyroid transcription factor-1 (TTF-1), and human epidermal growth factor receptor 2 (HER-2). These findings confirmed the diagnosis of PMA of the eyelid.\nGiven that an underlying occult malignancy of the gastrointestinal tract or breast may present similarly, she was evaluated extensively with CT scans of the thorax, abdomen, and soft tissues of the neck. She also had a mammogram and a colonoscopy. All the tests were unremarkable and negative for malignancy. Given the rarity of the disease, Radiation Oncology and Medical Oncology services were integrated to her care. She is being followed up in regular intervals and has not had any recurrence of her tumor thus far.