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.

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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.

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Background: The role of the mammalian target of rapamycin (mTOR) in hair follicle tumorigenesis is unclear. mTOR controls cell growth and can be activated through ribosomal S6 kinase.Herein, we sought to evaluate the expression of phospho-S6 in six different benign and malignant follicular tumor types.Methods: 76 cases were selected (17 fibrofolliculomas, 20 trichoepitheliomas, 10 tricholemmomas, 19 pilomatricomas, 1 malignant proliferating tricholemmal tumor, 8 tricholemmal carcinomas, and 1 trichoblastic carcinoma) and collected over 16 years. Immunohistochemistry with monoclonal antibody for phospho-S6 was performed and analyzed semi-quantitatively; statistical analysis using the χ 2 test was performed, with P < 0.05 considered significant. Results: All malignant neoplasms in our series (8/8 [100%] cases of tricholemmal carcinoma, 1/1 [100%] trichoblastic carcinoma, and 1/1 [100%] malignant proliferating tricholemmal tumor)showed a strong and diffuse pattern of staining for phospho-S6 involving 70% to 90% of tumor cells. By contrast, a minority of benign tumors were positive for phospho-S6 and most stained in a patchy pattern including 12/17 (71%) fibrofolliculomas, 9/20 (45%) trichoepitheliomas and 1/10 (10%) tricholemmomas, involving 30% to 50%, 5% to 20%, and 40% to 50% of tumor cells, respectively. Most pilomatricomas (17/19 [89%]) exhibited a stronger, but distinctive staining pattern, staining mostly the basaloid cells with a multifocal distribution, involving 70% to 90% of tumor cells.Conclusions: Phospho-S6 is differentially expressed among benign and malignant hair follicle tumors (P = 0.0044). While malignant tumors show diffuse expression, only a small subset of benign neoplasms were positive, primarily in a patchy distribution. K E Y W O R D Shair follicle tumors, mTOR pathway, phospho-S6

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.

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