Cutaneous Adenomyoepithelioma: Report of a Case and Review of the Literature.

Adenomyoepithelioma (AME) is a biphasic neoplasm of epithelial and myoepithelial cells. It is most commonly found in the breast, although rare cases have been reported from the lung, salivary glands, and skin. There are 5 well-documented cases of cutaneous AME in the literature. We report a new case of cutaneous AME. Our case was commingled with apocrine hidrocystoma. This is the first report of cutaneous AME in a male patient and the first to describe SOX10 immunostaining in cutaneous AME. We review the literature on cutaneous AME and note the greater than chance colocalization with other adnexal tumors. We speculate that AME may represent localized overgrowth of myoepithelial cells within a pre-existent sweat gland tumor. Histopathologists should be aware of the potential of SOX10-positive myoepithelial neoplasms to mimic nodular melanocytic proliferations.

"Apocrine Hidrocystoma and Cystadenoma"-like Tumor of the Digits or Toes: A Potential Diagnostic Pitfall of Digital Papillary Adenocarcinoma.

Digital papillary carcinoma (DPC) is a rare, underreported, and often misdiagnosed malignant tumor of the sweat glands. It is often located on the digits and toes and most commonly occurs in male individuals in their fifties to seventies. Because of lack of pain, slow growth, and an inconspicuous appearance, clinical diagnosis is often missed or delayed. In contrast, apocrine hidrocystoma (AH) is a cystic adenoma that arises from the apocrine secretory coil, and it is extremely rare for AHs to develop on the digits. We report 7 cases of DPC, including clinical course, histopathologic and immunohistochemical findings, and therapeutic approach in which the initial histopathologic diagnosis in all cases was AH or cystadenoma. However, complete excision of the neoplasms led to a final diagnosis of DPC. After an adequate treatment, no recurrence or metastasis was found in any of the cases described. All the cases studied showed similar histopathologic and immunohistochemical findings. The initial incisional biopsy showed large unilocular or multilocular cystic spaces situated within the dermis, lined by a double layer of epithelial cells with tiny papillary structures. No cellular atypia, necrosis, or pleomorphism was observed. However, complete excision revealed neoplastic lesions involving the dermis and/or subcutis, with an infiltrative pattern and papillary projections into luminal spaces. Immunoperoxidase studies showed positivity for CK7, S-100 protein, CEA, p63, smooth muscle actin, and calponin. DPC is a rare but life-threatening malignancy, therefore it is important to be able to identify such a lesion both clinically and histopathologically, treat it, and monitor the patient for the tumor's potential recurrence and metastasis. Pathologists and dermatopathologists should be aware that a histopathologic diagnosis of AH or cystadenoma on the fingers and toes should be established with caution, because probably those lesions represent the superficial and cystic component of an underlying DPC, and a wider excision should be performed.

A Comparative Study of Immunohistochemical Myoepithelial Cell Markers in Cutaneous Benign Cystic Apocrine Lesions.

The use of immunohistochemical markers for myoepithelial cells (MEC) is a useful tool in the distinction of benign from malignant epithelial neoplasms. Although their use in breast tumors is well recognized, little is known concerning its application in comparable cutaneous lesions. Using benign cutaneous cystic apocrine lesions as a study model, the aim of this study was to compare 5 immunohistochemical markers [calponin, p63, smooth muscle actin (SMA), cytokeratin 14, and CD10] in their effectiveness to highlight MEC. Cases of apocrine hidrocystoma and cystadenoma (n = 44) were reviewed with a particular emphasis on proliferative features and apocrine change. The MEC staining pattern and the intensity and distribution scores in proliferative (n = 29) and nonproliferative (n = 15) lesions were assessed, and the differences between the 2 groups were statistically analyzed using Fisher exact test. Calponin and SMA stained MEC in the most consistent manner. Being a nuclear stain, p63 was easy to interpret but typically showed discontinuous staining. Cytokeratin 14 not only effectively highlighted MEC but also stained some luminal epithelial cells in an unpredictable manner. Because of prominent background dermal fibroblast staining, CD10 was often difficult to interpret. Only SMA and p63 showed a statistically significant difference in MEC staining intensity scores between the proliferative and nonproliferative groups. Our results show that immunohistological staining for MEC in benign cystic apocrine lesions of the skin is variable. The authors recommend that a panel of markers that includes calponin and p63 be used and highlight the need for awareness of specific caveats associated with individual markers.

Her-2 expression in cutaneous eccrine and apocrine neoplasms.

Cutaneous eccrine and apocrine glands have many histologic and immunologic similarities to ducts and acini of the breast. Thus, differentiating a primary cutaneous process from a metastatic breast carcinoma can be nearly impossible. In all, 10-34% of breast carcinomas overexpress HER-2 protein, a membrane-associated protein that functions in cell differentiation, adhesion and motility. As expression of this gene in cutaneous neoplasms has not been well characterized, we sought to determine HER-2 expression in a sample of benign and malignant cutaneous eccrine and apocrine neoplasms and to determine if there is value in using this protein expression in differentiating primary cutaneous from metastatic breast lesions. Totally, 85 primary cutaneous neoplasms and 11 cutaneous metastases from HER-2-positive breast carcinomas were retrieved from archived material at our institute. All cases were evaluated for HER-2 protein expression using the Dako Hercept Test kit. Membranous HER-2 staining was noted in three of the 85 cutaneous adnexal neoplasms: one hidrocystoma and two nodular hidradenomas. Seven of the 11 cutaneous metastases from HER-2-positive breast carcinomas maintained moderate-to-strong HER-2 expression. In conclusion, while 10-34% of breast carcinomas overexpress the HER-2 protein, only 3.5% of cutaneous apocrine and eccrine neoplasms in this study stained with the HER-2 antibody. These HER-2-positive cutaneous neoplasms typically do not pose a diagnostic dilemma in the setting of differentiation from breast metastasis. Additionally, although histologically these breast and cutaneous lesions may have morphologic similarities, the relative lack of HER-2 overexpression suggests that they are different nosologically. Finally, this study suggests that HER-2 protein expression can be a useful tool in differentiating a primary cutaneous appendageal neoplasm from HER-2 expressing metastatic breast carcinoma.

Pigmented hidrocystoma of the eccrine secretory coil in the vulva: clinicopathologic, immunohistochemical and ultrastructural studies.

A case of pigmented hidrocystoma of eccrine secretory coil is presented. A 47-year-old woman had developed a bluish black small nodule in the anterior portion of the labium minor a few years before entry. Microscopically, the cyst was lined by eosinophilic columnar epithelium with abundant brownish granules. There was a vague suggestion of decapitation secretion focally in the epithelial layer of cuboidal cells. This layer expressed distinct reactivity against CA19-9 with no reactivity for human milk fat globule-1 (HMFG-1). These features demonstrated that the cyst was not of apocrine nature but of eccrine derivation. In addition, positive immunoreaction for cytokeratin (CK)7, CK8 and CK19 defined the cyst as originating from the secretory coil of the sweat gland. Ultrastructurally, melanosomes in various stages were identified in most of the epithelial cells. These findings suggest that the present case was a hidrocystoma of eccrine secretory coil with abnormal melanin accumulation.

Apocrine cystadenoma, apocrine hidrocystoma, and eccrine hidrocystoma: three distinct tumors defined by expression of keratins and human milk fat globulin 1.

Eccrine hidrocystomas and apocrine cystadenomas are morphologically related cystic sweat gland tumors. To elucidate their cellular differentiation we examined by immunohistochemistry the expression of keratins and of human milk fat globulin 1 in 12 of each of these tumors, diagnosed using established conventional histological criteria. All tumors diagnosed as apocrine cystadenomas by these criteria were characterized by a keratin pattern of secretory type. In addition, they expressed human milk fat globulin 1. Tumors diagnosed as eccrine hidrocystomas expressed a keratin pattern of excretory type. A part of the tumors with an excretory keratin pattern expressed human milk fat globulin, while others did not. Some presumed eccrine hidrocystomas expressed the very same antigens as apocrine cystadenomas. Thus, our study reveals three distinct types of tumors, in contrast to the conventional distinction of only eccrine hidrocystomas and apocrine cystadenomas. Apocrine cystadenomas differentiate towards the secretory coil of apocrine sweat glands. Presumed eccrine hidrocystomas may represent cystic tumors of the eccrine sweat duct, or they may represent cystic tumors of the apocrine duct. Thus, the name hidrocystoma should be used without further specification of an eccrine or apocrine nature, unless certainty is reached by immunohistochemical characterization. Also, hidrocystomas often prove to be histologically misdiagnosed apocrine cystadenomas because of a flattened cyst wall secondary to increased intraluminal pressure.