Unveiling idiopathic guttate hypomelanosis: pathology, immunohistochemistry, and ultrastructural study.

BACKGROUND: Idiopathic guttate hypomelanosis (IGH) is a pigment disorder of unknown etiology. Despite its high prevalence and the unaesthetic appearance of the lesions, there are relatively few histological studies on this disorder. This is an important gap to understanding its pathogenesis. OBJECTIVES: To assess the microscopic structure of IGH lesions compared to normal adjacent skin areas and the possible interaction between melanocytes and the subjacent dermis. METHODS: In this cross-sectional study, we took biopsy specimens of hypochromic lesions and adjacent normal skin from 20 patients with IGH. We analyzed the fragments using routine stains, immunohistochemistry, and electron microscopy. RESULTS: We found superficial dermal fibrosis in 90% (18/20) of our IGH cases and unreported keratinocyte cytoplasmic changes on electron microscopy. CONCLUSION: Our results suggest an interaction between melanocytes and the subjacent dermis in IGH. These findings can help to understand melanocyte biology and the pathogenesis of other achromic lesions.

Light and electron microscopy of chlorpromazine-induced hyperpigmentation.

Chlorpromazine may induce abnormal skin hyperpigmentation in exposed areas, described as slate-gray, purple, or blue-grayish discoloration. A 58-year-old man with schizophrenia, had been taking chlorpromazine for 5 years, and his sun-exposed skin areas exhibited a blue-grayish color. Large deposits of brown pigment and granular basophilic material were seen in the dermis with light microscopy. HMB-45 and anti-Melan-A antibody immunostaining labeled some pigment in the dermis. Transmission electron microscopy identified deposits among dermal collagen bundles collagen in both transverse and longitudinal sections. In the latter, an arboriform aspect of deposits was quite clear, and some melanophages were also seen. The three-dimensional examination of the dermis with scanning electron microscopy also identified deposits, which at higher magnification demonstrated an appearance in the shape of leaves, grass-like, interspersed with normal collagen. These results suggest a complex pathogenic mechanism, including deposition of dermal melanin together with drug itself and potentially additional unknown metabolites.

Ultrastructural aspects of primary anetoderma.

Anetoderma is a rare cutaneous disorder characterized by focal loss of dermal elastic tissue due to unknown mechanisms. Primary anetoderma develops on clinical normal skin, without any preceding dermatosis and it can be associated with autoimmune conditions. Secondary anetoderma develops on the same area of a previous disorder, such as infectious, neoplastic or inflammatory diseases. A 37-year-old female patient noticed for 4 years circumscribed, normochromic, asymptomatic herniated plaques on the trunk and upper limbs. Family history was negative. Only a positive antinuclear factor (ANF) test, with titer of 1:160 and nuclear homogeneous pattern was found. Light microscopy with Weigert staining showed a lessening of elastic fibers with fragmentation; the oxytalanic fibers were also affected or absent. Transmission electron microscopy showed fragmentation and granular degeneration of elastic fibers. With greater magnification, fragments similar to those seen with optical microscopy were identified. The collagen fibers did not present any alteration. The examination of the dermis with scanning electron microscopy also identified fragmentation and significant fissures of the elastic tissue, granular degeneration was also observed. With greater magnification fragmented elastic fibers were seen.

Most common patterns of acne in male adolescents: a population-based study.

BACKGROUND: Acne vulgaris is a common skin disease affecting more than 85% of adolescents and often continuing into adulthood. Population-based studies to assess the patterns and severity of acne have not been achieved. OBJECTIVES: The aim of this study was to assess the most common patterns of facial and trunk acne in young (18-year-old) men in a representative sample of male adolescents in a city in southern Brazil and to investigate the severity of inflammatory and non-inflammatory lesions in these individuals. METHODS: In Brazil, military service is compulsory for all males. Every adolescent male must report to his military service headquarters to submit to a medical screening examination. The study included 2201 adolescents, each of whom underwent a skin examination conducted by a dermatologist to identify and quantify all non-inflammatory (comedones) and inflammatory (papules, pustules, and nodules) lesions. RESULTS: Non-inflammatory lesions (comedones) were observed on 1487 individuals, and inflammatory lesions (papules and pustules) were noted on 1497 individuals. The most common patterns of facial acne were the full-face, bilateral malar and frontal mentonian distributions. CONCLUSIONS: This is the first population-based study to evaluate patterns of acne. Facial involvement was very prevalent, and the frontal region was found to dominate patterns of distribution of acne vulgaris. Comedonian acne of the face was much more intense and affected the entire face. In inflammatory facial acne, the majority of the study subjects exhibited up to five lesions in the region under study.

Light and electron microscopy of classical Ehlers-Danlos syndrome.

A 12-year-old boy with difficulty in wound healing and abnormal scars since early childhood was examined. Light microscopy showed loose and disperse dermal collagen with rare bundles, and fibroblasts show an irregular morphology. The fibrous sheath of hair presented a normal parallel distribution of the collagen fibers with normal spindle-shaped fibroblasts. Transmission electron microscopy also found disorganized collagen fibers, which were seen in a same field in longitudinal and cross sections. With high magnifications, an amorphous substance was seen near to loose collagen fibers, which showed variable diameters in cross sections. Scanning electron microscopy of the dermis showed disorganized collagen fibers and with higher magnification, important collagen disarrangement was observed with isolated and crossed-over fibers.

Serial light microscopy of experimental phytophotodermatitis in animal model.

BACKGROUND: Phytophotodermatitis (PPD) is a common phototoxic eruption, but very little information is available about its histological aspects, as the diagnosis is clinically established. METHODS: The epilated right half of the back of four albino rats was sprayed with peel juice of Tahiti lemon, one quadrant was exposed to sunlight for 5 min and the other for 8 min. The left back served as control. Biopsies were taken after 1, 2, 3, 4, 5, 6, 24, 48 and 72 h in both sides. RESULTS: The first six time intervals showed a normal epidermis in both sides. After 24 h, the area with peel lemon juice showed keratinocyte necrosis, cytoplasmic vacuolization and spongiosis in all rats, independent of the exposure time. The control side showed isolated keratinocyte necrosis with only 8 min of exposure. After 48 h, erythema is evident and strong vacuolization was observed, which progresses to sub- or intraepidermal blisters. After 72 h, the erythema persisted and histological findings were less intense. CONCLUSIONS: PPD can be successfully reproduced in rat skin. After 24 h spongiosis, vacuolization and keratinocyte necrosis are observed, clinically there are no changes. After 48 h, erythema appears with intra- and subepidermal blistering.