Cutaneous Adnexal Tumor With an Unusual Presentation-Discussion of a Potential Diagnostic Pitfall

Cutaneous Adenosquamous Carcinoma of the Scalp With Intestinal Phenotype

Cutaneous adenosquamous carcinoma is a mixed, squamous and glandular, rare malignant tumor of the skin characterized by a mixed, squamous, and glandular differentiation. Few cases of this tumor have been so far reported, and even fewer have been thoroughly studied by immunohistochemistry. We report here an exceptional case of cutaneous adenosquamous carcinoma which showed immunohistochemically features of intestinal differentiation, namely because of the expression of keratin 20 and CDX2, a marker of gastrointestinal tumors.

A unique case of a cutaneous lesion resembling mammary analog secretory carcinoma: a case report and review of the literature

Mammary analog secretory carcinoma (MASC) is a rare type of salivary gland tumor named for its morphological and genetic similarity to secretory carcinoma of the breast. These tumors are most often found in the parotid gland but have been described in several other mucosal locations of the head and neck. In this case report, a cutaneous lesion most closely resembling MASC was found in a neck mass of a 64-year-old male patient without evidence of a primary salivary gland or oral tumor. The lesion was excised, and the patient remains disease free to date. This case depicts a rare tumor in the skin most closely mimicking MASC and brings additional awareness to dermatopathologists of this tumor.

An Immunohistochemical Panel to Differentiate Metastatic Breast Carcinoma to Skin From Primary Sweat Gland Carcinomas With a Review of the Literature

Context.—Approximately 25% of patients with breast cancer develop cutaneous metastases. Sweat gland carcinomas (SGCs) account for about 0.05% of all cutaneous neoplasms. Cutaneous metastases of breast carcinoma (CMBCs) (especially the ductal type) can be difficult to distinguish from SGCs. Treatment and prognoses for these 2 types of tumors differ radically, making accurate histologic diagnosis crucial. Although a few studies attempt to differentiate these entities employing immunohistochemical (IHC) studies (some of which we review here), to date, no panel of IHC stains exists, to our knowledge, to distinguish these entities.

Objective.—To devise a panel of IHC stains to distinguish CMBC from SGC.

Design.—Twelve cases of ductal CMBCs (11 not otherwise specified type, and 1 basal phenotype), 11 cases of SGCs (5 eccrine carcinomas, 3 porocarcinomas, and 3 microcystic adnexal carcinomas), 2 benign sweat gland neoplasm cases, and 2 primary breast cancer cases were retrieved and analyzed with the following IHC panel: mammaglobin, gross cystic disease fluid protein (GCDFP) 15, p63, basal cytokeratins (CK5, CK14, and CK17), androgen receptor, and PAX5.

Results.—The p63 was only weakly expressed in 1 of 12 CMBC cases (8.3%), whereas it was strongly expressed in 10 of 11 SGC cases (90.9%) (P < .001). Basal cytokeratins demonstrated a similar immunoprofile in the SGC group, with 10 of 11 cases (90.9%) expressing all 3 markers, and a variable immunoprofile in the CMBC group with 0% (CK14) (P < .001) to 16.7% (2 of 12 cases; CK5 and CK17) (P < .001) expression. Mammaglobin was expressed in 8 of 12 cases (66.7%) of CMBC.

Conclusions.—Together, these 5 IHC stains were combined to make a panel that was 100% sensitive and 91% specific in distinguishing between CMBC and SGC.