Clinical and histological characteristics of poroid neoplasms: a study of 25 cases in Taiwan.

BACKGROUND: Eccrine poroma (EP) are relatively common benign eccrine neoplasms. Other poroid neoplasms (PNs), namely hidroacanthoma simplex (HS), dermal duct tumor (DDT), and poroid hidradenoma (PH), are seldom reported. METHODS: Among 18 653 biopsy specimens received from January 1988 to October 2003, we found 25 PNs (0.134%). We conducted retrospective analysis and obtained clinical and histopathological information. RESULTS: There were 16 EP, 3 HS, 4 PH, and 2 PH coexisting with either HS or EP. No DDT was found. More than half of PNs presented as red-color neoplasms, but none were diagnosed correctly on clinical grounds alone. The most common preoperative diagnoses were pyogenic granuloma or soft fibromas. Most EPs were located on hair-bearing regions of the limbs (37.5%) and trunk (25%), instead of soles (18.8%) and palms (6.3%). Three HS showed no cuticular cell, but had monomorphic poroid cells. Most EPs (10/16) were composed of both poroid and cuticular cells. All PH were composed of cuticular and poroid cells. Horn cysts were found in three cases (12%). Most PNs (16/25) contained clear cells. CONCLUSIONS: PNs are sudoriferous tumors that may vary considerably in clinical expression. EP, about 64% (16/25) of PNs in our series, was the most common. PH incidence is probably underestimated in the literature. We found six PHs in 25 PNs. Histopathologically, it is not justified to exclude PN diagnosis by noticing horn cysts. It was uncommon for two or three subtypes of PN to occur in a single lesion.

Towards a new classification of ectodermal dysplasias.

Ectodermal dysplasias (EDs) constitute a large and complex group of diseases characterized by various defects in hair, nails, teeth and sweat glands. Of the 170 EDs described so far, fewer than 30 have been explained at the molecular level with identification of the causative gene. This review proposes a new classification of EDs based on the function of the protein encoded by the mutated gene. The EDs are reviewed in light of the recent molecular and biochemical findings and an attempt is made to classify ED causative genes into four major functional subgroups: cell-cell communication and signalling; adhesion; transcription regulation; and development.

Disorders of sweating.

The clinical spectrum of sweating disorders includes sudomotor excess and deficiency. Hyperhidrosis is characterized by sweating beyond that required to maintain a constant internal body temperature. Hypohidrosis and anhidrosis are distinguished by a reduced or absent ability to generate sweat for the purpose of evaporative heat dissipation. Whereas hyperhidrosis is usually benign, anhidrosis may predispose to hyperthermia. Either hyperhidrosis or anhidrosis may accompany a more serious underlying disorder. Correct diagnosis depends on determining the anatomical pattern of sweating and localizing the lesion within the autonomic nervous system. Sudomotor deficits may involve the frontal operculum, hypothalamus, brain stem, spinal cord, sympathetic chain ganglia, peripheral nerve, or eccrine sweat glands. Treatments for hyperhidrosis include topical aluminum chloride, oral anticholinergic agents, intradermal botulinum toxin for some localized syndromes, and thoracic ganglionic sympathotomy or sympathectomy for refractory palmar hyperhidrosis.

[Morphology of sweat glands]. / Morphologie des glandes sudorales.

There are two types of sweat glands: eccrine glands, which do not show cytological changes during secretion and apocrine glands, characterised by decapitation secretion, in which part of the cell is pinched off and released into the lumen. Eccrine glands play a major role in thermoregulation and electrolyte balance. They are present everywhere in the human skin and are composed of a secretory portion, an intradermal duct and an upper intraepidermal part, called acrosyringium. The acrosyringium has a unique symmetrical and helicoidal course, which length is correlated to the thickness of the epidermis. Apocrine glands are located only on genital, axillary and mammary areas, where they are always connected to a hair follicle. Their exact role in humans is unknown. A third type of intermediate sweat glands, the apoeccrine glands, was recently described in axillary areas. Sweat glands can be involved in various inflammatory processes and can lead to a large range of both benign and malignant tumors.