The possible role of mast cells in pigmented nevi

Giant congenital melanocytic nevus with underlying hypoplasia of the subcutaneous fat

A 17-week-old boy with a giant congenital melanocytic nevus (GCMN) of the left lower extremity was noted to have a reduction in circumference of the left lower extremity relative to the contralateral side. The skin overlying the GCMN was persistently warm when compared with the surrounding and contralateral skin. Comparative plain radiography, ultrasonography, and magnetic resonance imaging showed fat hypoplasia of the left lower extremity, with bone and muscle appearing unaffected. The possible role of cytokines produced by the nevus in fat hypoplasia in GCMN is discussed.

Mast cells as modulators of hair follicle cycling

While the central role of mast cells (MC) in allergy and inflammation is well-appreciated, much less is known about their physiological functions. The impressive battery of potent growth modulatory MC products, and increasing evidence of MC involvement in hyperproliferative and fibrotic disorders suggest that tissue remodelling may be one of those, namely in the skin. Here, we delineate why this may best be studied by analysing the potential role of MC in hair growth regulation. On the background of numerous, yet widely under-appreciated hints from the older literature, we summarize and discuss our recent observations from the C57BL/6 mouse model for hair research which support the concept that MC are functionally important modulators of hair follicle cycling, specifically during anagen development. This invites to exploit the murine hair cycle as a model for dissecting the physiological growth modulatory functions of MC and encourages the exploration of MC-targeting pharmaceutical strategies for the treatment of hair growth disorders.

Mast cell numbers in melanocytic naevi and cutaneous neurofibromas

This study aimed to determine the diagnostic utility of mast cell densities in distinguishing neurotised ("neural") melanocytic naevi from neurofibromas. Three groups of lesions were studied: neurofibromas, neural naevi, and naevi showing no neural change (control naevi). A Giemsa stain was used to demonstrate mast cells. The median mast cell density in the neurotised naevus group was significantly higher (p < 0.005) than that of both the neurofibroma and control naevus groups, but the distributions of the individual density counts overlapped considerably. The sensitivity and specificity of the mast cell density as a potential discriminator between neurotised naevi and neurofibromas, determined in relation to the optimal discrimination value obtained using Bayes' minimum cost decision rule, were low. It is concluded that mast cell density on its own is of little use as a classification tool but could be of value in the context of a multivariate decision rule.

Frequency of mast cells in the olfactory mucosa of rhesus monkeys

During studies of the olfactory mucosa and its response to the different levels of circulating sex hormones, considerable numbers of mast cells have been observed in its epithelia and subepithelial regions. The number of these cells in the olfactory mucosa of male monkeys differs greatly from that found in females. The frequency of these cells in the olfactory mucosa of females fluctuates significantly during the menstrual cycle. These fluctations stimultaneously correspond to the well known changes in olfactory sensitivity: around ovulation, when the olfactory sensitivity for certain odorants is high, the number of mast cells in the olfactory mucosa also increases.

Histophysiology of mast cells in skin and other organs

Our observations demonstrate an intimate relationship between peripheral nerve fibers and mast cells. In addition, mast cells in various organs influence both the small blood vessels and the organ parenchyma cells. These relations are interpreted in the sence of a neuro-hormonale feedback-system.