Acanthoma

Abstract: Clinical and histopathologic features of 40 new examples of trichilemmoma were analyzed. Lesions were almost invariably solitary, asymptomatic, and located on the face. Two-thirds of the patients were men; median age was 59 years; median duration was a few months; and clinical impression was frequently basal cell carcinoma or verruca. Histopathologic examination frequently disclosed lobular acanthosis of glycogenrich clear cells oriented about a follicle. At the edge of the lesion, a palisade of columnar cells, that resembled the outer root sheath of a hair follicle, rested on a wellformed basement membrane. Trichilemmoma must be differentiated from other clear cell tumors of skin, including Degos acanthoma, clear cell hidradenoma, basal cell carcinoma, sebaceous neoplasms, other follicular tumors such as inverted follicular keratosis and tumor of follicular infundibulum, and metastatic renal carcinoma.

Abstract: Background: Dermatoscopy (dermoscopy, epiluminescence microscopy) is used for the early detection of malignant tumors and avoidance of unnecessary excisions of benign skin tumors. Objective: Description of the dermatoscopic pattern of clear-cell acanthoma. Methods: Video dermatoscopy at 20-fold magnification of a clear-cell acanthoma and psoriasis vulgaris. Results: Homogeneous, symmetrically or bunch-like arranged, pinpoint-like capillaries were seen in the clear-cell acanthoma and in psoriasis vulgaris. Conclusion: The dermatoscopic psoriasis-like pattern of clear-cell acanthoma is a diagnostic clue which may help the clinician to identify this benign epidermal tumor and to differentiate it from other benign and malignant tumors of the skin.

Abstract: Clear-cell acanthoma (CCA) has been reported to be a benign epidermal neoplasm; however, several authors have suggested alternative differentiation as well as other nosologic categories, including a reactive dermatosis. Fourteen CCAs, ten tricholemmomas, and seven cases of psoriasis were reviewed with conventional microscopy, periodic acid-Schiff stains, and immunohistochemical stains. Twelve of fourteen (86%) CCAs were associated with underlying or adjacent conditions. The CCAs stained immunohistochemically in a pattern similar to normal epidermis and psoriasis. Tricholemmomas stained in a distinctly different pattern with MNF116 and NGFR/p75. These cases demonstrate CCA in settings that reflect chronic inflammation, primarily scars and stasis dermatitis, and with an immunophenotype that parallels psoriasis. These findings support the contention that CCA does not show outer follicular sheath (tricholemmal) differentiation. Furthermore, these cases lend additional support to the contention that CCA represents a psoriasiform reaction pattern, which, in appropriately taken biopsies, usually has a demonstrable associated condition. Nonetheless, the precise nosology of this phenomenon has yet to be elucidated completely.

Abstract: :Among the tumors of the epidermal appendages, only rare tumors have been proved as differentiating in the direction of the nail. Beside onychomatricoma, we report a new matrical tumor of the nail: onychocytic matricoma (acanthoma of the nail matrix producing onychocytes). The main different