Solitary keratoacanthoma: a self-healing proliferation that frequently becomes malignant.

To discuss the relation between solitary keratoacanthoma (KA) and crateriform squamous cell carcinoma (cSCC), the clinical and histologic features of cutaneous crateriform squamous cell proliferations were studied. Two hundred twenty cases of wholly excised crateriform squamous cell proliferations were studied both clinically (age, sex, location, and duration) and histologically (hematoxylin-eosin-stained sections). For comparison, we studied 100 consecutive cases of wholly excised noncrateriform squamous cell carcinoma (ncSCC).

[Report of a case of T-cell peripheral lymphoblastic lymphoma in an HIV patient].

T-cell lymphomas in human immunodeficiency virus infections are rare, first case have being described in 1987, by Presant. Our purpose is to report the first T-cell Lymphoma case without epidermotropism in an HIV patient in Extremadura, and pioneer in Spain. Clinic extensive and histopathologic studies of cutaneous lesions were realized, including monoclonal antibodies tests.

Pseudo-Kaposi sarcoma induced by minor trauma in a patient with Klippel-Trenaunay-Weber syndrome.

Arteriovenous malformations (AVM) are vascular anomalies containing a communication between an artery and a vein without an intervening capillary bed. In 1990, Klippel and Trenaunay reported a patient with limb overgrowth, cutaneous angiomata and varicose veins. In 1918, Parkes Weber mentioned the additional feature of AVM terming the condition 'hemangiectatic hypertrophy'.

Basal cell carcinoma with matrical differentiation.

Three cases of basal cell carcinoma showing shadow cells within basaloid islands have been described using the term basal cell carcinoma with matrical differentiation for this histologic variant. We present four new cases of basal cell carcinoma with evidence of matrical differentiation. Unlike the cases previously published, these lesions showed nests of shadow cells either within the lobules of basaloid cells or forming nests in the stroma.

Epidermotropic metastases from internal carcinomas.

Four cases of epidermotropically metastatic carcinoma are reported. One of them originated from a breast adenocarcinoma; in two other cases, the primary tumor was located in the large intestine; and, in the fourth case, the primary malignancy was a laryngeal squamous cell carcinoma. Clinically, the cutaneous metastases were nodular lesions and histologically, in addition to the involvement of the dermis by malignant cells, in three cases there was intraepidermal involvement by glandular structures.

Trichilemmal cyst under a compound melanocytic nevus.

Cystic dilatation of a hair follicle, folliculitis, abscess formation and epidermoid cysts are not infrequent findings in an intradermal melanocytic nevus. We herein report a trichilemmal cyst under a compound melanocytic nevus. To the best of our knowledge this association has not been previously reported.

Achromic verrucous large cell acanthoma.

Large cell acanthoma (LCA) is an epidermal neoplasm whose nature has been variously explained. Though frequently hyperpigmented, we describe for the first time an achromic case located on the dorsum of the right hand of a 83-year-old woman. This observation is largely inconsistent with one of the theories about the nature of this condition: that it is merely a solar lentigo with large nuclei of keratinocytes.

Aggressive keratoacanthoma of the eyelid: "malignant" keratoacanthoma or squamous cell carcinoma?

We report an aggressive keratoacanthoma of the upper eyelid that recurred at the site of a previously excised keratoacanthoma. The diagnosis was confirmed by biopsy. Because the surgery required would be extensive, medical therapy was tried first.

Angiolymphoid hyperplasia with eosinophilia limited to the vulva.

A patient with angiolymphoid hyperplasia with eosinophilia is described. This is, to our knowledge, the first case report in which the lesions were located on the vulva.

Cutaneous lymphangiectases after therapy for carcinoma of the cervix--a case with unusual clinical and histological features.

Secondary lymphangioma (lymphangiectasis) has been reported as a consequence of lymphatic damage. No specific histological criteria can be used to differentiate primary lymphangioma circumscriptum from lymphangiectasis. We describe a woman who developed lymphangiectases on both non-lymphoedematous upper thighs after hysterectomy and radiation therapy for carcinoma of the cervix.

Periungual porocarcinoma.

We describe a patient who developed a porocarcinoma in the nail bed. His profession had exposed him to X-rays for many years, resulting in chronic radiodermatitis of several digits on both hands. He displayed an ulcer in the lateral nail fold of the right third digit which extended into the nail bed.

Clear-cell syringoma. Immunohistochemistry and electron microscopy study.

Clear-cell syringoma is a histologic variant of syringoma that is otherwise clinically indistinguishable from ordinary syringoma. This variant is formed by cells that have pale or clear cytoplasm as a result of glycogen accumulation. There is a high association of clear-cell syringoma and diabetes mellitus.