Sebaceous differentiation in microcystic adnexal carcinoma

Sclerosing Microcystic Adenocarcinoma of the Head and Neck Mucosa: A Neoplasm Closely Resembling Microcystic Adnexal Carcinoma

Microcystic adnexal carcinoma (MAC) occurs predominantly in the centrofacial skin and has been only rarely reported in mucosal surfaces. We here present a 5 case series of tumors closely resembling MAC occurring in the mucosal surfaces of the head and neck, which we have termed sclerosing microcystic adenocarcinomas. These tumors showed a predilection for women (4:1) with an average patient age of 52.6 years (range 41-73 years). Location included the tongue (n = 2), the floor of the mouth (n = 2), and the nasopharynx/clivus (n = 1). One occurred after radiation therapy and another occurred in the setting of immune compromise. Immunohistochemistry highlighted a dual cell population with luminal cells showing positivity for high and low-molecular weight keratins and surrounding myoepithelial cells showing S100 and smooth muscle actin staining. No cases had nodal involvement, and the single patient with clinical follow-up was alive and free of disease 34 months after diagnosis and definitive radiochemotherapy. Differential diagnoses for all cases diverged from those provoked by MAC in the skin and included a variety of salivary gland neoplasms such as adenoid cystic carcinoma, polymorphous low grade adenocarcinoma, and mucoepidermoid carcinoma. Recognition of sclerosing microcystic adenocarcinoma in the head and neck mucosa is critical given its bland appearance and subtle infiltration pattern, infrequency of nodal involvement, and behavioral differences from the other entities on the differential.

Microcystic adnexal carcinoma: an immunohistochemical reappraisal

Even though immunohistochemical comparisons of microcystic adnexal carcinoma vs infiltrative basal cell carcinoma and desmoplastic trichoepithelioma exist, they are mostly restricted to the use of a single stain. In addition, a comparison with squamous cell carcinoma has not been reported previously. In this study, we compare the expression of cytokeratin (CK) 15, CK7, CK20, CK903, carcinoembryonic antigen (CEA), CD10, CD15 and BerEP4 in 13 microcystic adnexal carcinoma, eight desmoplastic trichoepithelioma, 10 infiltrative basal cell carcinoma, and eight squamous cell carcinoma of which five exhibited ductal differentiation. We found that the majority of microcystic adnexal carcinoma (92%) and desmoplastic trichoepithelioma (100%) cases expressed CK15 while the infiltrative basal cell carcinoma and squamous cell carcinoma cases were all negative. Forty percent of infiltrative basal cell carcinoma expressed CK7; while only two microcystic adnexal carcinoma cases (15%) and one squamous cell carcinoma with ductal differentiation (12%) expressed CK7 in the remaining three tumor categories. None of the desmoplastic trichoepithelioma expressed CK7. All tumors were strongly positive for CK903. While the neoplastic cells were negative, luminal staining of ductal structures was noted for CK7, CD15 and CEA in some of the microcystic adnexal carcinoma, desmoplastic trichoepithelioma and squamous cell carcinoma with ductal differentiation cases. Sixty percent of infiltrative basal cell carcinoma, 31% of microcystic adnexal carcinoma, and 25% of squamous cell carcinoma express CD10. BerEP4 expression was noted in 38% of microcystic adnexal carcinoma, 57% of desmoplastic trichoepithelioma, 100% of infiltrative basal cell carcinoma, and 38% of squamous cell carcinoma. In conclusion, we found CK15 to be a useful marker in distinguishing microcystic adnexal carcinoma from infiltrative basal cell carcinoma and squamous cell carcinoma with ductal differentiation. Our experience indicates that microcystic adnexal carcinoma and desmoplastic trichoepithelioma have a similar immunohistochemical profile that is, CK15+ and BerEP4+/-; thus, additional studies are needed to separate these two entities.

Apocrine mixed tumor of the skin (“mixed tumor of the folliculosebaceous-apocrine complex”)

BACKGROUND

A systematic analysis of the entire spectrum of various forms of differentiation and metaplastic epiphenomena in cutaneous apocrine mixed tumor (AMT) has never been performed.

OBJECTIVE

The purpose of our study was to study a large number of cutaneous mixed tumors so as to fully characterize the entire spectrum of differentiations and metaplastic changes that may occur in the epithelial, myoepithelial, and stromal components of AMT.

METHODS

This article reports a light-microscopic study of 244 cases of cutaneous AMT, complemented by a literature review.

RESULTS

All types of differentiation along the lines of the folliculosebaceous-apocrine unit can be seen in AMT. The spectrum of metaplastic changes in the epithelial components includes squamous metaplasia, mucinous metaplasia, oxyphilic metaplasia, clear cell change, columnar metaplasia, hobnail metaplasia, and cytoplasmic vacuolization. The following changes in the myoepithelial component were documented: clear cell change, hyaline cells, plasmacytoid cells, spindling, and collagenous spherulosis. Stromal alterations included chondroid metaplasia, osseous metaplasia, and adipose metaplasia.

LIMITATIONS

This study utilizes tissue specimens that mainly came as consultations; therefore some inherent selection bias exists.

CONCLUSIONS

AMT displays a wide range of differentiation and metaplastic changes in its epithelial, myoepithelial, and stromal components. These phenomena are not mutually exclusive. When unduly prominent, they may present diagnostic pitfalls. Our findings corroborate those of previous publications, stressing the remarkable diversity of differentiation and metaplasias that may be found in cutaneous AMT. We propose that the most appropriate name for these lesions is "mixed tumor of the folliculosebaceous-apocrine complex."

Cutaneous Sebaceous Neoplasms With a Focal Glandular Pattern (Seboapocrine Lesions): A Clinicopathological Study of Three Cases

Presented here are three cutaneous sebaceous tumors (one carcinoma and two sebaceomas), each demonstrating a focal glandular pattern representing apocrine differentiation. The patients, two males and one female, each clinically presented with a small solitary nodule or tumor on the scalp. None of the patients had features of Muir-Torre syndrome. Surgical removal of the lesions was performed in all cases. None of the patients developed recurrence or metastasis after surgery (follow-up ranged from 18 to 24 months). The glandular areas represented a minor but significant component of the lesions and appeared as glands of various complexity, mostly as simple round or elongated tubular structures lined by a row of cuboidal to columnar cells with eosinophilic cytoplasm and round nuclei, with or without a distinct nucleolus. Decapitation secretion was evident but not prominent. In both sebaceomas, at least a portion of the glands had a peripheral small-cell layer that appeared similar to the basal/myoepithelial cells of normal eccrine and apocrine ducts. In some glands, the basal/myoepithelial cells seemed to have undergone hyperplasia, resulting in two or more rows of cells that even formed small islands, with an overall appearance reminiscent of basal cell hyperplasia in the prostate, arising in the basal layer of the prostatic glands. The descriptive terms seboapocrine carcinoma or seboapocrine sebaceoma are proposed for such lesions. These tumors may be viewed as rare histopathological variants of sebaceous carcinoma and sebaceoma, with a second type of differentiation along the lines of the folliculosebaceous-apocrine unit.

Low-grade Adnexal Carcinoma of the Skin With Multidirectional (Glandular, Trichoblastomatous, Spiradenocylindromatous) Differentiation

The conjoint occurrence of follicular, sebaceous, or apocrine differentiations in a cutaneous adnexal neoplasm is a known event, more often encountered in benign neoplasms, whereas reports of cutaneous malignant adnexal tumors with bilineage or trilineage differentiation are few. A new case of a cutaneous malignant adnexal neoplasm with multidirectional differentiation is reported here. A 57-year-old woman presented with a long-standing, slowly growing, asymptomatic solitary tumor the size of a large nut in the coccygeal area, which was surgically excised. Ten years after the surgery, there was no evidence of recurrence or metastasis. Microscopically, the neoplasm was located in the dermis with focal extension into the subcutis. It was asymmetric, horizontally oriented, and mostly composed of small nodules that varied in shape from round and oval aggregations to elongated strands and irregular islands; the nodules were either clustered, formed a jigsaw puzzle-like pattern or were dispersed. The nodules were composed of small basaloid cells sometimes intermixed with larger cells with ample cytoplasm forming glandular structures. Rare nodules resembled elements seen in a spiradenoma by containing scattered lymphocytes and globules of hyalinized eosinophilic basal membrane material. The stroma was paucicellular, but focally it resembled that seen in perifollicular mesenchyme. Mitotic figures, including abnormal ones, were infrequent, but mild nuclear pleomorphism, nuclear crowding, and individual cell necrosis were easily appreciable in both small basaloid cells and cells with clear cytoplasm. Perineural invasion was apparent. We classified this tumor as a well-differentiated adnexal carcinoma demonstrating combined follicular and apocrine differentiation. It differs from previously published cases of malignant adnexal tumors with multidirectional differentiation and further exemplifies the spectrum of diversity encountered in malignant proliferations with differentiation toward the folliculosebaceous-apocrine unit.

Eccrine duct carcinoma of the eyelid mimicking meibomian carcinoma: clinicopathological study of a case

Eccrine duct carcinoma belongs to a group of malignant sweat gland tumors showing de novo eccrine differentiation, but without features of benign adnexal counterparts. They are therefore likely to be confused with visceral adenocarcinomas that have metastasized to the lid. These tumors require important diagnostic considerations when adenocarcinoma is encountered in the lid in the absence of a known primary tumor. We present the case of a 60-year-old man with a nodule in the right upper eyelid that was histopathologically diagnosed as eccrine duct carcinoma of the lid. The differential diagnosis of eccrine carcinomas based on light microscopy, enzyme histochemistry, and immunohistochemistry is discussed, and a list of the various malignant eccrine tumors reported in the lid is presented.

Microcystic adnexal carcinoma: an uncommon tumor with debatable origin

BACKGROUND

Microcystic adnexal carcinoma is an uncommon skin appendage neoplasm exhibiting both pilar and sweat duct differentiation. This tumor remains a subject of controversy as to its differentiation profile, histogenesis, and classification which is reflected in the nomenclature used to designate the neoplasm in question. Beyond this controversy the tumor remains a diagnostic challenge because of its rarity, the histologic mimicry it may display, and its banal cytologic appearance; it also poses a therapeutic challenge, as it is characterized by slow but aggressive and destructive local growth extending beyond clinical margins together with a high tendency for perineural invasion and recurrence.

OBJECTIVE

We report two cases of this unusual tumor illustrating some of its characteristics. Our review emphasizes the divergent opinions concerning its differentiation profile and its origin. An organoid nevus as the origin of microcystic adnexal carcinoma in one of our patients is discussed in this context.