Cutaneous manifestations of a zoonotic Onchocerca species in an adult male, acquired in Nova Scotia, Canada.

A 65-year-old male with known hypertension and hypercholesterolemia sought medical attention because of a 3-month history of skin swelling on his upper back. Histopathology and molecular techniques were employed and identified an organism in the Onchocerca genus. This represents a very uncommon example of cutaneous infection by a zoonotic Onchocerca species.

Evolution of granuloma annulare to mid-dermal elastolysis: report of a case and review of the literature.

A 55-year-old healthy Caucasian female, on no medication, was seen by a dermatologist because of a patchy, slightly indurated and violaceous eruption involving her neck and trunk. The clinical impression was of granuloma annulare (GA). Over a period of several months the violaceous lesions became atrophic with loss of colour and eventual wrinkling of lesional skin. Sequential skin biopsies were obtained, which revealed a spectrum of changes. Those from early violaceous lesional zones displayed perivascular lymphocytic infiltrates and interstitial granulomatous inflammation, characteristic of interstitial GA. Samples from atrophic lesional areas appeared normal on routine sections but an Orcein-Giemsa (OG) stain, prompted by the clinical history of atrophy, revealed absence of elastic fibers in the mid-reticular dermis. The combined clinicopathologic findings pointed to development of mid-dermal elastolysis (MDE) at involutional sites of GA. Owing to consideration of a cutaneous T-cell lymphoma in the differential diagnosis, genotyping in search of T-cell monoclonality was performed and yielded a negative result. Our case supports the existing but scant evidence in the literature that the rare, enigmatic condition termed MDE is an end-result of inflammatory destruction of dermal elastic fibers. GA is one form of dermatitis capable of culminating in this entity, but others have also been implicated.

Solid carcinoma revisited: a possible variant of microcystic adnexal carcinoma.

Primary malignant apocrine and eccrine skin neoplasms are rare and their nosology is still evolving. First described in 1997, solid carcinoma is now considered a discrete entity by some, although this remains controversial. Apocrine differentiation was postulated. A single case since then was the first to include immunohistochemistry findings. The authors report an additional case of solid carcinoma, together with its immunohistochemical profile. A 63-year-old man presented with a firm nodule 3 cm in diameter on the posterior scalp. On punch biopsy, the lesion was interpreted as an adnexal neoplasm of indeterminate malignant potential. The subsequently excised tumor was initially interpreted as microcystic adnexal carcinoma with perineural invasion involving the surgical margins. Re-excision yielded clear surgical margins. After review of all the histologic material, a final diagnosis of solid carcinoma was rendered. Histologically, innumerable solid aggregations of neoplastic epithelial cells filled the dermis and extended into the subcutis. The aggregations varied in size and ranged from round or ovoid nests to elongated columns or cords embedded within a fibrotic stroma. The neoplastic cells were round and uniform in size with small nuclei and pale or clear cytoplasm. Tubular structures and mitoses were absent. Solid carcinoma is a rare skin neoplasm. Histologically, it closely resembles and may be indistinguishable from the solid areas of microcystic adnexal carcinoma. Biologically, solid carcinoma, like microcystic adnexal carcinoma, is an indolent but relentless locally destructive neoplasm that must be removed completely. The clinical, histologic, and biologic similarities suggest that solid carcinoma may be a variant of microcystic adnexal carcinoma.

Pure versus combined Merkel cell carcinomas: immunohistochemical evaluation of cellular proteins (p53, Bcl-2, and c-kit) reveals significant overexpression of p53 in combined tumors.

Merkel cell polyomavirus is of oncogenic significance in approximately 80% of Merkel cell carcinomas. Morphological subcategories of the tumor differ in regard to viral status, the rare combined type being uniformly virus negative and the predominant pure type being mainly virus positive. Indications that different biological subsets of the tumor exist led us to explore this diversity. In an Eastern Canadian cohort of cases (75 patients; mean age, 76 years [range, 43-91]; male/female ratio, 43:32; 51 [68%] pure and 24 [34%] combined tumors), we semiquantitatively compared the immunohistochemical expression of 3 cellular proteins (p53, Bcl-2, and c-kit) in pure versus combined groups. Viral status was known in a subset of cases. The significant overexpression of p53 in the combined group (mean [SD], 153.8 [117.8] versus 121.6 [77.9]; P = .01) and the increased epidermal expression of this protein (p53 patches) in the same group lend credence to a primary etiologic role for sun damage in these cases. Expression of Bcl-2 and c-kit did not differ significantly between the 2 morphological groups. A relative increase in c-kit expression was significantly associated with a virus-negative status (median [interquartile range], 100 [60-115] versus 70 [0-100]; P = .03). Emerging data reveal divergent biological pathways in Merkel cell carcinoma, each with a characteristic immunohistochemical profile. Virus-positive tumors (all pure) exhibit high retinoblastoma protein and low p53 expression, whereas virus-negative cases (few pure and all combined) show high p53 and relatively high c-kit expression. The potential biological implications of this dichotomy call for consistent stratification of these tumors in future studies.