E. Sanchez Yus

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). One hundred forty-four of the 220 cases of crateriform squamous cell proliferations were histologically classified as KA. In 47 other cases, a relatively large area of the KA showed frank histologic and cytologic malignant transformation (mKA); this event could happen during every stage of the KA. Twenty-nine lesions were cSCCs without remnants of KA. The patients in the KA group were significantly younger (p = 0.000) than those in the other three groups. The ages of the patients in these three groups were not significantly different (p = 1.0). More KAs (16%) were located in areas that are not usually exposed to the sun than was the case with the other groups of neoplasms considered (2%, 3%, and 3%, respectively), and this difference was statistically significant (p = 0.001). Regarding the duration of the lesion, only the differences between KA and cSCC, KA and ncSCC, and mKA and ncSCC were statistically significant. Not every cutaneous crateriform squamous cell proliferation is a KA; in KA, the crater must be multilocular, the “lips” must be perforated, and the cornified contents do not usually project out of the “mouth.” At least a quarter of KAs undergo malignant transformation, which occurs more frequently in older patients and photoexposed areas. This transformation is a focal event and may happen at any stage of KA development. Consequently, a suspected KA must be wholly excised and studied in serial paraffin blocks so as to disclose any focus of malignant transformation.

Follicular hybrid cysts : an expanded spectrum

Currently it is well established that each of the three parts of the hair follicle (infundibulum, isthmus, and the inferior portion) originates different types of cutaneous cysts. Thus, follicular cysts include infundibular, trichilemmal. and matricial cysts. Brownstein in 1983 described a mixed type of cutaneous cyst combining epidermoid. infundibular, and trichilemmal types of keratinization. We review and illustrate the different combinations of follicular hybrid cysts reported to date: infundibular and trichilemmal cyst, infundibular and pilomatricoma cyst, trichilemmal and pilomatricoma cyst, eruptive vellus hair cyst and steatocystoma, and eruptive vellus hair cyst and trichilemmal cyst. Therefore, the concept of hybrid cyst should not be restricted to those composed of infundibular and trichilemmal cysts, because any cyst arising from the various parts of the pilosebaceous unit can combine with others to form a large series of follicular hybrid cysts.

Pigmented spindle cell naevus

We report 22 cases of pigmented spindle cell naevus (PSCN). The usual appearance of these naevi is that of a heavily pigmented papule found mostly on the legs of young patients. Histologically, PSCN was characterized by symmetrical proliferation of spindle‐shaped pigmented melanocytes grouped in large junctional nests. Pagetoid spread of single cells in the overlying epidermis was frequently found. In our opinion, PSCN is a distinctive benign acquired melanocytic naevus that in the past has been frequently misdiagnosed as atypical Spitz naevi or malignant melanoma.

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. In the fourth case, the cutaneous metastatic tumor cells showed striking “folliculotropism.” We review the literature of epidermotropically metastatic carcinoma and discuss its differential diagnosis.

Sclerosing‐sweat‐duct (microcystic adnexal) carcinoma—a tumour from a single eccrine origin

A patient with a sclerosing‐sweat‐duct carcinoma of the upper lip is reported. Histologically the tumour showed solid islands and strands of squamous cells and sparse small ductal structures, some of them containing central cores of dense eosinophilic keratin. All this was embedded in a sclerotic stroma. These features, in addition to positive immune‐reactivity for carcinoembryonic antigen (CEA) in the lumina of small ducts, and the presence of S‐100 protein‐positive cells in some cords and ducts, are consistent with the notion that this tumour exhibits differentiation toward eccrine sweat structures.

Agminated Blue Nevi: Case Report and Review of the Literature

Blue nevi may rarely appear in multiple form and grouped in a circumscribed area, a pattern of arrangement that is more properly designed under the term agminated blue nevi. In this paper a new case with light and ultrastructural studies is described, and the previously reported cases are reviewed. Histologically, there was a characteristic perifollicular arrangement of dermal melanocytes, most of which showed ultrastructurally an extracellular sheath. Agminated blue nevi seem to be benign lesions, but because of their rarity, no definite prognosis can be given.

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‐lymphoedcmatous upper thighs after hysterectomy and radiation therapy for carcinoma of the cervix.

Clear-Cell Syringoma

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

Clear cell syringoid eccrine carcinoma

: A case of syringoid eccrine carcinoma (SEC) is reported. The tumor was mainly formed by clear cells laden with glycogen. This feature, rarely found in syringoma, had not previously been reported in SEC. The authors assume that SEC is an infiltrating and locally destructive but not metastasizing neoplasm. They propose that SEC is a clinicopathologic entity with a histopathologic spectrum from the more differentiated syringomatoid ones to so-called primary cutaneous adenoid cystic carcinoma. A possible nexus between the more syringomatoid cases and the sclerosing sweat duct (syringomatous) carcinoma is also discussed.

Neutrophilic eccrine hidradenitis: a report of two additional cases

Neutrophilic eccrine hidradenitis is a new neutrophihc dermatosis recently reported in association with acute myelogenous leukaemia and other malignancies, usually occurring during chemotherapy. The authors report two new cases, one of which was a patient with chronic lymphocytic leukaemia who had been treated with chlorambucil for 2 years. The clinical and histopathologi‐cal features of the published cases are reviewed and the possible pathogenesis of this new syndrome is discussed.