So-called neoplastic myoepithelial cells in chondroid syringomas/mixed tumors of the skin: their subtypes and immunohistochemical analysis

Mixed tumour of the skin of the lower lip: A case report and review of the literature

Mixed tumour of the skin or chondroid syringoma (CS) is a rare and mostly benign neoplasm of the sweat glands. Although CS is frequently located on varied parts of the head and neck region, the lower lip is a rarely reported site. The present report describes a case of CS of the lower lip in a 58-year-old male as an expository case to further emphasise the need for proper diagnosis, appropriate treatment and prognostic evaluation. The patient presented with a round, non-tender, slightly hard and mobile mass beneath the mucocutaneous junction of his left lateral side of the lower lip. Radiology revealed a mass measuring 11x11x7 mm³ in size at a depth of ~2 mm. Furthermore, magnetic resonance T1- and T2-weighted images showed slightly low and high signal intensities, respectively. A provisional diagnosis of benign tumour of the lower lip was made, and surgical excision biopsy taken under local anaesthesia, while considering the patient's cosmetic appearance. Histopathology demonstrated features akin to apocrine gland, chondroid and myxoid stroma consistent with the diagnosis of benign CS. No evidence of recurrence or satellites were recorded after a follow-up of nearly 2 years. Although rare, a high index of suspicion for CS among other cutaneous adnexal tumours of the lower lip is necessary. In addition, interprofessional collaboration in the management of such oral tumours could enhance patient satisfaction amid prevailing intraoral and aesthetic concerns.

Clinical and pathological study on mixed tumors of the skin

Mixed tumor of the skin (MTS) is a rare benign tumor of the sweat glands with a reported frequency of 0.01% to 0.098%. The objective of the study is to investigate clinicopathological and immunohistochemical features of mixed tumor of the skin.This was a retrospective study of 21 patients diagnosed with MTS at the Institute of Dermatology and Venereology of Sichuan Provincial People's Hospital from 1980 to 2016. Pathological sections of all cases were reread and the diagnosis was verified.There were 14 males (67%) and 7 females (33%). MTS affected the face. The lesions were skin-colored or lightly red, with no subjective symptoms in most cases. Histopathologically, the tumors consisted of epithelial and interstitial components. The epithelium was mainly composed of cubic or polygonal cells, which can be seen within the tubule-like structures with bilayer epithelium. The inner cells mainly expressed cytokeratin and other epithelial markers. The outer cells expressed epithelial and mesenchymal markers. The outer cells expressed S-100, P63, and glial fibrillary acidic protein. The tumors showed interstitial mucus-like and fibrosis changes, and some parts had cartilage-like changes.Pathological diagnosis is particularly important because the clinical symptoms of MTS lack specificity.

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."

CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells in the tumor capsule of skin sweat gland neoplasms

To elucidate the roles of CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells at the tumor border of skin sweat gland neoplasms, we examined expression of stromal cell markers in the tumor capsule of 19 skin sweat gland neoplasms (16 mixed tumors of the skin and three nodular hidradenomas) using monoclonal antibodies to CD34, CD31, cytokeratin 14 (CK14), alpha-smooth muscle actin (ASMA) and high molecular weight caldesmon (HCD). We regarded CD34-positive, CD31-, CK14-, ASMA- and HCD-negative stromal cells to be CD34-positive stromal cells, and ASMA-positive, HCD-, CK14-, CD34- and CD31-negative stromal cells to be ASMA-positive stromal cells. CD34-positive stromal cells were detected in the tumor capsule of all 19 of the tumors examined. In nine of the 16 mixed tumors (56%) and all of the three nodular hidradenomas, ASMA-positive stromal cells were detected at the immediate inner side of the CD34-positive stromal cell layers. These results indicate that cellular components in the tumor capsules of mixed tumors of the skin and nodular hidradenomas are CD34-positive stromal cells and ASMA-positive stromal cells, and suggest that stromal cells of these two cell types are associated with tumor capsule formation of skin sweat gland neoplasms.

Benign chondroid syringoma: report of a case clinically mimicking a malignant neoplasm

Chondroid syringoma, or mixed tumor of skin, is an uncommon sweat gland tumor most often seen in the head-and-neck region of patients in the sixth or seventh decade. Tumors usually present as asymptomatic, slowly growing masses. Histologically, there are both epithelial and stromal components. The treatment of choice is local excision. Rare malignant examples have been reported, commonly involving the extremities. We present a case of cutaneous chondroid syringoma arising in the thigh of a 28-year-old female. The tumor grew over a 4-year period, increasing rapidly in size over the last few months with fixation and pigmentation of the overlying skin clinically mimicking a malignant neoplasm. Such cutaneous appendage tumors are uncommon, and surgeons may be unfamiliar with them.

Myoepithelioma of the lacrimal gland: report of a case with potentially malignant transformation

Myoepithelioma of the lacrimal gland is extremely rare and only four cases, one of which was malignant, have been reported in detail. The present report describes a case of lacrimal gland myoepithelioma in a Japanese male with histological features suggestive of potentially malignant transformation. The excised tumor consisted of two components, a central nodular component and a peripheral component surrounding the former. These components were separated by a fibrous tissue. Microscopically, both components were comprised almost entirely of spindle-shaped cells, but with some epithelioid cells containing glycogen granules. Extracellular spaces in the peripheral component were filled with eosinophilic materials with the occasional crystalloid structures, which were immunoreactive for collagen type I. Neoplastic cells were immunoreactive focally for vimentin and S-100, but negative for cytokeratins, epithelial membrane antigen, muscle actin, smooth muscle actin, desmin, myosin, and glial fibrillary acidic protein. The neoplastic cells in the central component showed nuclear pleomorphism and atypia with a higher frequency of mitotic figures, and higher labelings of proliferation markers than those in the peripheral component. Neither invasion, necrosis, nor hemorrhage was observed in the tumor. From these findings we proposed a diagnosis of potentially malignant myoepithelioma.

Myoepithelioma of soft tissue

A myoepithelioma occurred in the subcutaneous tissue of the right shoulder of a 28-year-old man. The well-demarcated nodular tumor (3. 0 x 2.8 cm) was located in the subcutaneous tissue with no adhesion to the deltoid muscle. The tumor was composed of a fascicular proliferation of spindle cells with variable amounts of stroma and showed areas of sheets of epithelioid cells. In most areas, the tumor cells had uniform nuclei, but pleomorphic epithelioid cells were focally present. Mitotic activity was three per 10 high-power fields. No ductular structure was found throughout the tumor. Immunohistochemical and ultrastructural studies confirmed the myoepithelial origin of the tumor cells. The occurrence of myoepithelioma in the subcutaneous tissue has been rarely reported. Even though the tumor showed no aggressive behavior on the 2-year follow-up, it is still too early to comment definitely on the behav- ior of myoepithelioma of the subcutaneous tissue. This case provides further information about soft tissue myoepithelioma.