Clear-cell acanthoma versus acanthosis: a psoriasiform reaction pattern lacking tricholemmal differentiation.

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.

Pulmonary sclerosing hemangioma with lymph node metastases: report of 4 cases.

CONTEXT: Sclerosing hemangioma is an unusual pulmonary tumor. Previously, 4 patients with pulmonary sclerosing hemangioma and lymph node metastases have been described in the literature. OBJECTIVE: To report 4 additional cases of metastatic sclerosing hemangioma. DESIGN: Retrospective review of the authors' consultation files and review of histologic sections of pulmonary tumors and lymph node metastases. RESULTS: Four cases of a morphologically benign pulmonary sclerosing hemangioma with regional lymph node metastases (including hilar, peribronchial, and interlobar metastases) were identified. The patients (3 female, 1 male) had a mean age of 39 years (range, 10-56 years). The tumors ranged in size (greatest dimension) from 1.5 to 4.7 cm (mean, 3.1 cm). The pulmonary tumors were typical circumscribed sclerosing hemangiomas without mitotic activity, angiolymphatic invasion, or necrosis. One tumor had focal cytologic atypia. The metastases were identified in hilar lymph nodes that were removed at operation for the lung nodule. One patient received adjuvant chemotherapy for adenocarcinoma. All of the patients are alive. No recurrences or residual disease has been detected at a mean follow-up of 4.7 years (range, 2.3-10 years). CONCLUSIONS: On the basis of case data from the 4 patients described here and the 4 patients described previously, metastases to regional lymph nodes from pulmonary sclerosing hemangioma may occur but are rare and do not appear to affect prognosis.