Search results for "Outer root sheath"
showing 4 items of 4 documents
Migration of Melanoblasts into the Developing Murine Hair Follicle Is Accompanied by Transient c-Kit Expression
2002
Disruption of the c-Kit/stem cell factor (SCF) signaling pathway interferes with the survival, migration, and differentiation of melanocytes during generation of the hair follicle pigmentary unit. We examined c-Kit, SCF, and S100 (a marker for precursor melanocytic cells) expression, as well as melanoblast/melanocyte ultrastructure, in perinatal C57BL/6 mouse skin. Before the onset of hair bulb melanogenesis (i.e., stages 0–4 of hair follicle morphogenesis), strong c-Kit immunoreactivity (IR) was seen in selected non-mela-nogenic cells in the developing hair placode and hair plug. Many of these cells were S100-IR and were ultrastructurally identified as melanoblasts with migratory appearanc…
Diagnostic value of CD34 immunostaining in desmoplastic trichilemmoma.
1998
Desmoplastic trichilemmoma (DT) is a variant of trichilemmoma, characterized by a central prominent desmoplastic component which may simulate invasive carcinoma. We have studied the morphologic and immunohistochemical features of seven cases of DT. Immunohistochemistry was performed on paraffin sections using monoclonal antibodies to CD34 (QBEND/10), vimentin and GCDFP-15. CD34 was also tested in seven cases of basal cell carcinoma (BCC), three with outer root sheath differentiation and four with morphea-form features, and five squamous cell carcinomas. Histologically, features of conventional trichilemmoma were seen at the periphery of the seven lesions. In contrast, at the center, the epi…
Cytokeratin 20 Is a General Marker of Cutaneous Merkel Cells While Certain Neuronal Proteins Are Absent
1995
Merkel cells are difficult to identify in tissue sections. Previous studies have used cytokeratins (CK) 8, 18, and 19 as histologic markers of Merkel cells. However, these CKs are also expressed in some outer root sheath keratinocytes and some early fetal epidermal cells and thus are not truly specific of Merkel cells in general. Using selective antibodies against a newly described CK, number 20--originally found in intestinal epithelium and Merkel cell carcinomas--in comparison to a key protein of neuroendocrine cells, chromogranin A, we established CK 20 as a specific Merkel cell marker in skin of humans, pigs, and mice. CK 20 seems to be an even more general and sensitive Merkel cell mar…
Pigmented desmoplastic trichilemmoma
2016
Desmoplastic trichilemmoma (DT), the pseudomalignant variant of conventional trichilemmoma described by Hunt et al in 1990, displays a superficial lobular growth pattern of glycogen-rich cells with peripheral nuclear palisading surrounded by a thickened basement membrane. DT differs from its conventional counterpart by showing a central hyalinized area with epithelial cords and strands mimicking invasive carcinoma. We report a case that fully satisfies the criteria for DT and, in addition, shows an extensive melanocytic cell component and prominent melanin deposition. To our knowledge, a pigmented variant of DT has not been reported and should be recognized in order to appropriately face th…