Demodex mites.

Demodex mites are normal inhabitants of human hair follicles. D folliculorum is found predominantly in the follicular infundibulum of facial skin and is typically present in small groups. D brevis, the smaller of the two species, predominates on the trunk, typically as solitarily mites within the sebaceous glands and ducts. In a wide variety of animals, Demodex mites are recognized as a cause of mange. The role of Demodex mites as agents of human disease has been more controversial, but evidence favors their involvement in acneiform eruptions, folliculitis, and a range of eruptions in immunosuppressed patients.

Treatment of common skin infections and infestations during pregnancy.

In the absence of systematic studies in pregnant and lactating women, recommendations for the treatment of infections during pregnancy are based on animal studies, accumulated evidence from clinical use and case reports, as well as published consensus statements and expert opinion. This article examines the evidence basis for the treatment of common cutaneous infections in women who are pregnant or breast-feeding.

Elastic staining versus fluorescent and polarized microscopy in the diagnosis of alopecia.

BACKGROUND: Recently, polarized microscopy was reported as helpful in the evaluation of alopecia biopsy specimens. OBJECTIVE: We sought to determine the usefulness of polarized microscopy relative to elastic tissue staining and fluorescent microscopy. METHODS: Histologic sections from 60 alopecia specimens were evaluated to determine the pattern of elastic tissue in elastic van Gieson-stained sections. Comparable hematoxylin-eosin sections were examined under a fluorescent microscope to determine the elastic tissue pattern and examined under polarized microscopy to determine the pattern of birefringence. RESULTS: Elastic van Gieson staining demonstrated high sensitivity (1.0) and high specificity (1.0) for the identification of nonscarring alopecia. In 54 of 60 cases, fluorescent microscopy demonstrated an identical pattern of elastic tissue. High background eosin fluorescence made it impossible to interpret the elastic tissue pattern in the remaining 6 specimens. Strong birefringence in dermal collagen sparing fibrous tracts had high specificity (1.0) but lower sensitivity (0.59). Strong collagen birefringence within the dermis and broad fibrous tracts were present in all 6 cases of central centrifugal cicatricial alopecia. LIMITATIONS: Elimination of the 6 uninterpretable specimens with high background fluorescence from our calculations may be a source of bias, as these cases could potentially all have been either negative or positive. CONCLUSION: Elastic tissue staining is the most reliable means to determine the pattern of scarring in alopecia biopsy specimens. In most cases, fluorescent microscopy of hematoxylin-eosin sections shows an identical pattern. Although a pattern of collagen birefringence on polarized microscopy distinctly sparing fibrous tract is specific for nonscarring alopecia, not all cases of nonscarring alopecia demonstrate this pattern. Strong collagen birefringence within both the dermis and fibrous tracts suggests a diagnosis of central centrifugal cicatricial alopecia.

The staining pattern of pigmented spindle cell nevi with S100A6 protein.

BACKGROUND: Spitz nevi typically show strong diffuse staining with S100A6, whereas staining in melanomas is commonly patchy and weak. To our knowledge, S100A6 has not been studied in pigmented spindle cell nevus (PSCN), considered by many to be a variant of Spitz nevus. METHODS: Forty-six archived PSCNs were stained with S100A6 and then categorized by predominant cell size and staining pattern. RESULTS: Eighteen (55%) of the small cell predominant nevi showed patchy staining, eight showed diffuse staining and seven were negative for S100A6. Two predominantly large-celled 'PSCNs' were diffusely positive and had many histopathological attributes of classical Spitz nevi. On review, these two cases were reclassified as Spitz nevi and excluded from the remainder of this study. Of the nevi with mixed cell size, one had no expression of S100A6. In the remaining tumors, the small cells showed patchy staining in eight (80%) and diffuse staining in two (20%). The large cells showed patchy staining in four (40%) and diffuse staining in six (60%). CONCLUSION: In contrast to the strong diffuse S100A6 staining typical of Spitz nevi, the small spindle cells of PSCN commonly show patchy staining or fail to stain completely. In melanocytic neoplasms composed of small spindle cells, patchy S100A6 staining should not be interpreted as evidence of supporting a diagnosis of melanoma.