Basal cell carcinoma--signet ring type. Ultrastructural study

Basal cell carcinoma with signet ring cell morphology accumulating the ubiquitinated cytokeratin 5/6

Basal cell carcinoma (BCC) showing signet ring (SR) cell morphology is a very rare variant of BCC. Here, we report BCC with SR cell morphology developed in the right cheek skin of a 79-year-old man. Histopathologic examination showed irregularly shaped islands of basaloid cells with characteristic peripheral palisading. Inside of the cancer islands, many tumour cells showed an enlarged fine granular cytoplasm with the peripherally compressed nuclei, being similar to the SR cell. Immunohistochemical examination revealed dense accumulation of cytokeratin (CK) 5/6 and a faint signal of 34βE12 in SR cells. The reported myoepithelial markers were not detected. Interestingly, ubiquitin, a component of the ubiquitin-proteasome protein degradation system, was co-localised in the SR cells. These suggest, for the first time, that accumulation of the undegraded CK5/6 with ubiquitination results in the SR cell morphology. Our report showed that the aberrant keratin turnover is associated with the SR cell BCC.

Hyaline Inclusion Acanthoma

ABSTRACT

Eosinophilic hyaline inclusions (EHIs) or globules have been reported in various cutaneous tumors including vascular lesions, myoepithelial neoplasms, and basal cell carcinoma. In basal cell carcinoma, the presence of intracytoplasmic inclusions is reportedly associated with myoepithelial differentiation. In this regard, EHI has not been conclusively documented in a cutaneous lesion of genuine squamous cell lineage without aberrant differentiation. In the current case, a biopsy from the right thigh of a 71-year-old male patient demonstrated a relatively well-demarcated intraepidermal squamous lesion featured an admixture of predominantly enlarged keratinocytes harboring distinct eccentric intracytoplasmic EHI and a smaller population of keratinocytes displaying pale cytoplasm. Cytologic atypia, mitotic activity, and inflammatory cells were not identified. The intracytoplasmic EHI stained red with Masson's trichrome and were negative with periodic-acid Schiff with and without diastase. Immunologically, the lesion was strongly and diffusely positive for various cytokeratins but negative for ubiquitin and myoepithelial markers. Only cytokeratin AE1 revealed a differential staining pattern as the suprabasal lesional cells displayed significantly stronger immunoreactivity in comparison with the adjacent normal keratinocytes. Polymerase chain reaction for low-risk and high-risk human papillomavirus was negative. Molecular studies did not reveal any mutations commonly encountered in seborrheic or lichenoid keratoses. As an analogous lesion has not previously reported in the literature, the term hyaline inclusion acanthoma is proposed for this peculiar lesion.

Basal Cell Carcinoma with Myoepithelial Differentiation: Case Report and Literature Review

Basal cell carcinoma is the most common skin cancer. Myoepithelial cells are specialized epithelial cells. Basal cell carcinoma with myoepithelial differentiation is a rare tumor. A 71-year-old man with a basal cell carcinoma with myoepithelial differentiation that presented as an asymptomatic red papule of two months duration on his forehead is described. Including the reported patient, this variant of basal cell carcinoma has been described in 16 patients: 11 men and five women. The patients ranged in age at diagnosis from 43 years to 83 years; the median age at diagnosis was 66 years. All of the tumors were located on the face—most were papules or nodules of less than 10 x 10 mm. Their pathology demonstrated two components: one was that of a typical basal cell carcinoma and the other was myoepithelioma-like in which the tumor cells were plasmacytoid or signet ring in appearance and contained abundant eosinophilic cytoplasm or hyaline inclusions or both. The myoepithelial tumor cells had variable immunohistochemical expression that included not only cytokeratin but also actin, glial fibrillary acid protein, S100, and vimentin. The most common clinical impression, prior to biopsy, was a basal cell carcinoma. The pathologic differential diagnosis included cutaneous mixed sweat gland tumor of the skin, myoepithelioma, myoepithelial carcinoma, and tumors that contain a prominent signet ring cell component (such as metastatic gastrointestinal and breast carcinoma, melanoma, plasmacytoid squamous cell carcinoma, and T-cell lymphoma). Mohs micrographic surgical excision, with complete removal of the tumor, was recommended for treatment of the carcinoma.

Basal cell carcinomas showing histological features generally associated with cutaneous adnexal neoplasms

Basal cell carcinoma (BCC) is the commonest malignant neoplasm in humans. Although a histopathological diagnosis of BCC is straightforward in the vast majority of cases, unusual histological variants can present a diagnostic challenge. A small proportion of BCCs show features which are generally associated with cutaneous adnexal neoplasms. Such changes may involve either the epithelium or the stroma and can mislead the pathologist particularly in small biopsies. Despite the growing evidence which speculate that BCC is a primitive follicular tumor, it is unusual to encounter tumors which actually show definitive signs of adnexal differentiation. This review aims to address this somewhat overlooked aspect of a very common tumor and offers practical guidance to distinguish them from adnexal neoplasms which they might mimic.

Primary cutaneous signet-ring cell melanoma with pseudoglandular features, spindle cells and oncocytoid changes

The authors report a 69-year-old man with a primary nodular malignant melanoma on the shoulder showing unusual histological features. It mostly consisted of markedly neoplastic melanocytes, which exhibited abundant clear cytoplasm compressing the nuclei to the periphery, resulting in a signet-ring appearance. In other areas of the melanoma, there were focally desmoplastic and pseudoglandular patterns and oncocytoid changes. Immunohistochemical studies showed that the tumor cells were uniformly positive only for S-100 protein and vimentin. Signet-ring cell melanoma is a rare histopathological variant of malignant melanoma with only a few described cases. To the best of our knowledge, this is the first case reporting a combination of the signet-ring cell melanoma with desmoplastic, pseudoglandular, and oncocytoid features.

Basal cell carcinomas with unusual histologic patterns

Uncommon histologic variants of basal cell carcinoma (BCC) can present a diagnostic challenge. In this case series, we describe 3 patients with unusual BCCs encountered in a dermatologic surgical unit over a 1-year period from September 2003 to September 2004. The formalin-fixed, paraffin-embedded histologic specimens were initially examined microscopically after staining with hematoxylin and eosin. Additional stains, including diastase periodic acid-Schiff, colloidal iron, carcinoembryonic antigen, and cytokeratin-20, were subsequently performed as appropriate. Of the 3 lesions, one exhibited apocrine differentiation and two demonstrated a trabecular growth pattern. Although BCCs demonstrating apocrine differentiation have previously been described, a trabecular growth pattern, to our knowledge, has not been previously reported for BCC.

Signet ring basal cell carcinoma. A case study emphasizing the differential diagnosis of neoplasms with signet ring cell formation

Signet ring cells are cells in which the nucleus is crescentically compressed to the cellular border so that the cells look like signet rings. Due to the pluripotential nature of the basal cells of the epidermis, basal cell carcinoma displays many histopathological variants. We herein report the rare case of a middle-aged woman who had a basal cell carcinoma on the skin of the upper lip. The neoplasm was predominantly composed of cells with signet ring configuration. Histochemically, the latter were mucin-negative. Immunohistochemistry demonstrated intracytoplasmic reactivity for cytokeratin MNF116 with strong staining intensity, as well as for smooth muscle actin. The signet ring tumor cells were S100 protein-negative and carcinoembryonic antigen-negative. The lack of ploidy abnormality as well as of molecular alterations in K-ras and p53 genes may explain in part the non-aggressive biological behavior of the present tumor. Because of potential diagnostic difficulties, the pathologist should be aware of this unusual form of basal cell carcinoma. A brief review of the literature on the differential diagnosis of signet ring cell cutaneous tumors is presented.

Signet ring cell basal cell carcinoma: a basal cell carcinoma with myoepithelial differentiation

Basal cell carcinoma (BCC) can show a variety of routes of differentiation, but myoepithelial differentiation has rarely been described. We describe a case of BCC showing histologic and immunohistochemical features of myoepithelial differentiation. Histologically, the lesion showed well-demarcated tumor nodules composed of two different components. One component was typical of BCC, and the other component was composed of tumor cells containing abundant cytoplasm, eccentric nuclei, and no peripheral palisading, with scattered signet ring-shaped cells. Immunohistochemically, the tumor cells in the typical BCC component stained with CKAE1/AE3 and smooth muscle actin (SMA), but not with S-100 protein. They stained weakly with CAM5.2, epithelial membrane antigen, and glial fibrillary acidic protein (GFAP). The tumor cells in the other component stained strongly with CKAE1/AE3 and SMA, moderately with epithelial membrane antigen and GFAP, and weakly with CAM5.2. In a small area, the tumor cells stained with S-100 protein.

Basal cell carcinoma metastatic to the salivary glands: differential diagnosis in fine-needle aspiration cytology

A disparate group of salivary gland neoplasms is characterized by small, uniform, hyperchromatic, basaloid cells. This "small blue cell" pattern is most common in non-Warthin's types of monomorphic adenoma, or in adenoid cystic carcinoma. Small cell anaplastic carcinoma (primary or metastatic), metastatic basaloid squamous cell carcinoma, basal cell adenocarcinoma, and metastatic nasopharyngeal carcinoma are rarely encountered but may present a cytologically similar appearance. We report one female and two male patients (median age = 84 yr) with cutaneous-type basal cell carcinoma (BCC) aspirated from metastatic deposits in the parotid (2 cases) or the submandibular (1 case) gland. One was correctly classified at the time of aspiration, based on a previous history of multiple facial BCC. One was interpreted as carcinoma, the previous history being unavailable at the time of FNA. Smears in these two cases show necrosis and rare keratotic cells. The third cases was mistaken for pleomorphic adenoma (PA); the smears showed metachromatic fragments of collagenous tumor stroma that were misinterpreted as the matrix material typical PA. Similar material was identified in the other two cases. When the "small blue cell" pattern is encountered in salivary bland cytology, one should consider BCC, especially if necrosis is identified. The desmoplastic tumor stroma of BCC may mimic the chondroid matrix of PA. Careful consideration of previous history is very important.

Basal cell carcinoma with hyaline inclusions

A 69 yr old man had a 4 mm basal cell carcinoma completely excised from the chin. Numerous hyaline cytoplasmic inclusions were contained within the tumor cells. The inclusions stained intensely red with Masson's trichrome, and immunocytochemically there was prominent rim labelling for keratins (bovine, callus and AE1/3) and muscle-specific actin, the latter more faintly decorating the centre of some inclusions. The inclusions were negative for antibodies to cytokeratin Cam5.2, epithelial membrane antigen (EMA), vimentin, S100, neurofilaments, glial fibrillary acidic protein (GFAP) and carcinoembryonic antigen (CEA) and there was no post Congo red apple green birefringence to indicate amyloid. Ultrastructure indicated the inclusions were composed of proteinaceous material surrounded by a defined rim of tonofilaments in cells showing no degenerative features. The findings suggested aberrant tumor cell keratinization. Familiarization with this rare variant of a common cutaneous carcinoma will alleviate diagnostic difficulties that may arise, particularly in superficial tumor curettage.

Clear cell basal cell carcinoma: an unusual degenerative variant

Clear cell basal cell carcinoma (BCC) is an unusual variant of BCC which is characterized by a variable component of large clear cells. Twenty cases are presented which are further subdivided into pure, mixed, or metatypical categories. Although initially thought to represent sebaceous or tricholemmal differentiation, electron microscopic studies demonstrated that the clear cell changes are a degenerative phenomenon, probably involving lysosomes.

Metastatic signet-ring cell melanoma in a patient with an unknown primary tumor. Histologic, immunohistochemical, and ultrastructural findings

Signet-ring cell melanoma is a rare morphologic variant of malignant melanoma. We describe a 27-year-old man with widespread cutaneous and internal metastases of an unknown primary tumor. One skin biopsy specimen and a fine-needle aspirate showed polygonal tumor cells consistent with the diagnosis of metastatic melanoma, but a second skin biopsy specimen revealed neoplastic cells with a signet-ring cell appearance. Both specimens, however, yielded identical immunohistochemical findings. Tumor cells were positive for vimentin and S-100 protein and reacted with the melanoma markers HMB-45 and NKI-C3. Ultrastructural studies revealed abundant intermediate filaments in the cytoplasm of the signet-ring cells. Based on these findings, a diagnosis of metastatic melanoma was made. In this report we describe the fourth case of metastatic signet-ring cell melanoma, and discuss how malignant melanoma may lead to metastases that have divergent morphologic appearances in the same patient.

Hyaline inclusions in a synovial sarcoma following intra-arterial chemotherapy

Hyaline inclusions were noted in cells of a typical synovial sarcoma following intra-arterial chemotherapy. Ultrastructural study revealed that the inclusions were cytoplasmic aggregates of intermediate filaments. Since the inclusions were not present in the tumor prior to treatment, it is suggested that they may have formed as a result of the infusion and that their presence may be an indicator of chemotherapeutic effect.

Aggregates of cytofilaments as the cause of the appearance of hyaline tumor cells

Cells resembling the hyaline cells of mixed salivary tumors have been identified in islet cell tumors, basal cell carcinoma, epithelioid leiomyoma, and an hepatic apudoma. Cytofilaments of intermediate size were present in these cells of electron microscopy and the distinctive hyaline appearance of cytoplasm is ascribed to large aggregates of these.