Wolfgang Hartschuh

Muir-Torre Phenotype Has a Frequency of DNA Mismatch-Repair-Gene Mutations Similar to That in Hereditary Nonpolyposis Colorectal Cancer Families Defined by the Amsterdam Criteria

Muir-Torre syndrome (MTS) is an autosomal dominant disease defined by the coincidence of at least one sebaceous skin tumor and one internal malignancy. About half of MTS patients are affected by colorectal cancer. In a subgroup of MTS patients the disease has an underlying DNA mismatch-repair (MMR) defect and thus is allelic to hereditary nonpolyposis colorectal cancer (HNPCC). The purpose of this study was to examine to what extent germ-line mutations in DNA MMR genes are the underlying cause of the MTS phenotype. We ascertained 16 MTS patients with sebaceous skin tumors and colorectal cancer, and we examined their skin and visceral tumors for microsatellite instability. All the patients exhibited high genomic instability in at least one tumor. The search for germ-line mutations in the hMSH2 and hMLH1 genes in 13 of the MTS patients revealed truncating mutations in 9 (69%): eight mutations in the hMSH2 gene and one in the hMLH1 gene. This is the first systematic search for germ-line mutations in patients ascertained on the basis of sebaceous skin tumors. Our results indicate that (1) MTS patients exhibit significantly more mutations in the hMSH2 gene than in the hMLH1 gene; and (2) the subpopulation of MTS patients who are also affected by colorectal cancer, irrespective of family history and age at onset of tumors, may have a likelihood for an underlying DNA MMR defect similar to that for patients with a family history fulfilling the strict clinical criteria for HNPCC.

Met enkephalin-like immunoreactivity in Merkel cells.

SummaryThe Merkel cells from sinus hair follicles of rats were investigated by immunohistochemistry using different antisera against neuropeptides and gastroenteropancreatic (GEP)-hormones. For the first time it has been demonstrated that Merkel cells exhibit an immunoreactivity towards metenkephalin (methionine-enkephalin). The met-enkephalin immunoreactivity was restricted to Merkel cells and was not found in associated nerve axons or terminals. Denervation of Merkel cells did not affect the met-enkephalin immunoreactivity. Antisera against leu-enkephalin (leucine-enkephalin) and other polypeptides did not produce an immunoreaction.The demonstration of met-enkephalin-like immunoreactivity supports the concept that the Merkel cell is a member of the paraneuronal system and a potential neuroreceptor cell.

Peptidergic (neurotensin, VIP, substance P) nerve fibres in the skin. Immunohistochemical evidence of an involvement of neuropeptides in nociception, pruritus and inflammation

In recent years potent vasoactive effects have been demonstrated in various organs including the skin (Lembeck & Donnerer, 1981) for the biologically active neuropeptides neurotensin (NT), vasoactive intestinal polypeptide (VIP) and substance P (SP) (cf. Hokfelt et al, 1980; Pernow, 1980; Uhl & Snyder, 1980). There is increasing evidence that NT, VIP and SP act as neurotransmitters in some peripheral systems, e.g. NT is a neurotransmitter candidate in the heart (Quirion et al, 1980; Reinecke et al, 1982), VIP probably has neurotransmitter function in the gastrointestinal tract (Fahrenkrug, 1980; Said, Giachetti & Nicosia, 1980) and SP seems to be a transmitter of primary sensory neurons involved in pain perception (Hokfelt et al, 1975; Henry, 1980). In addition, it has recently been shown that SP and, even more potently, KT and VIP cause pruritus after intradermal injection (Hagermark, 1982). To date, SP (Hokfelt et al, 1975). NT (Weihe, Hartschuh & Reinecke, 1981a) and VIP (Weihe et al, 1981b) have been localized immunohistochemicaliy in nerve fibres of the skin only in separate or preliminary studies. However, no histotopographical analysis of the distribution of NT, VIP and SP in the skin has been carried out so far. The present study presents a systematic comparative analysis ofthe localization of these neuropeptides in the skin of several mammalian species, including man. Various regions of human skin (fingertip, arm, axilla, toe tip, prepuce, scrotum, mamilla) and similar regions of some other mammalian species (guinea-pig, rat, cat, dog, monkey) were investigated for the distribution of NT-, VIP-, and SP-immunoreactive (IR) nerve fibres. The specimens were dissected, Bouin-fixed and embedded in paraffin. The immunohistochemical reactions were carried out using the peroxidase-antiperoxidase (PAP) technique modified after Forssmann et al. (i98r). The antisera used (anti-NT, code HC-8, donated by Dr S.E.Leeman; Carraway & Leeman, 1976; anti-VIP, code R 501, donated by Dr N.Yanaihara; Dimaline^ Vaillant & Dockray, 1980; anti-SP, code RRF 9/5, own; Reinecke et al, 1982) showed no

Classifying ambiguous melanocytic lesions with FISH and correlation with clinical long-term follow up

Recently, initial studies describing the use of multicolor fluorescence in situ hybridization (FISH) for classifying melanocytic skin lesions have been published demonstrating a high sensitivity and specificity in discriminating melanomas from nevi. However, the majority of these studies included neither histologically ambiguous lesions nor a clinical long-term follow up. This study was undertaken to validate a special multicolor FISH test in histologically ambiguous melanocytic skin lesions with known clinical long-term follow up. FISH was scored by three independent pathologists in a series of 22 melanocytic skin lesions, including 12 ambiguous cases using four probes targeting chromosome 6p25, centromere 6, 6q23, and 11q13. The FISH results were compared with array comparative genomic hybridization data and correlated to the clinical long-term follow up (mean: 65 months). Pair-wise comparison between the interpretations of the observers showed a moderate to substantial agreement (κ 0.47–0.61). Comparing the FISH results with the clinical behavior reached an overall sensitivity of 60% and a specificity of 50% (χ2=0.25; P=0.61) for later development of metastases. Comparison of array comparative genomic hybridization data with FISH analyses did not yield significant results but array comparative genomic hybridization data demonstrated that melanocytic skin lesions with the development of metastases showed significantly more chromosomal aberrations (P<0.01) compared with melanocytic skin lesions without the development of metastases. The FISH technique with its present composition of locus-specific probes for RREB1/MYB and CCND1 did not achieve a clinically useful sensitivity and specificity. However, a reassessment of the probes and better standardization of the method may lead to a valuable diagnostic tool.

VIP-immunoreactivity in the skin of various mammals: Immunohistochemical, radioimmunological and experimental evidence for a dual localization in cutaneous nerves and Merkel cells

In the present study VIP-immunoreactive (IR) nerve fibers were found in the skin of several mammalian species (cat, dog, pig and man). They supplied predominantly the arteries and arterial portions of arteriovenous anastomoses. Far fewer VIP-IR nerve fibers innervated veins and arterioles. Capillaries were supplied by VIP-IR fibers only in sweat and Meibomian glands. Some non-vascular VIP-IR nerve fibers were seen in contact with dermal smooth muscle strands. In eccrine sweat glands and in Meibomian glands VIP-IR fibers were targeting glandular cells. In addition, VIP-IR nerve fibers innervated the upper parts of facial hair follicles. In non-neuronal localization VIP-IR occurred in Merkel cells in all species and sites, while the intraepidermal axons consistently were not VIP-IR. Radioimmunoassay of different skin regions of cats also suggested both a neuronal and a Merkel cell origin of VIP-IR. Under physiological conditions VIP which is released from its neuronal and non-neuronal cutaneous pools may have an impact on thermoregulation by influencing blood flow and sweat production. It may also modulate axon-endings in Merkel cell-axon complexes and hair follicle receptors. Under pathological conditions an enhanced release of cutaneous VIP may lead to local inflammatory processes partly mediated via release of histamine from cutaneous mast cells.

Cytokeratins as markers of follicular differentiation: an immunohistochemical study of trichoblastoma and basal cell carcinoma.

Trichoblastoma(s) (TB) are benign neoplasms of follicular differentiation frequently found in nevus sebaceus. Many morphologic features are shared with nodular basal cell carcinoma(s) (BCC), sometimes rendering the differential diagnosis difficult. Because both neoplasms can simulate components of mature hair follicles histologically, we attempted to corroborate this by immunohistochemical examination of cytokeratins and hair keratins differentially expressed in the hair follicle. Trichoblastoma(s) and BCC showed homogenous expression of CK14 and CK17. The innermost cells of the tumor nodules in all TB and in 72% of BCC were positive for CK6hf. Using a specific CK15 antibody, 38% of TB showed a focal labeling and all BCC remained negative; 70% of TB and 22% of BCC expressed CK19. CK8 was expressed by numerous Merkel cells present in all TB but in none of the BCC examined. All type I and II hair keratins tested, (especially hHa1, hHa5, and hHa8) remained negative in all tumors examined. Trichoblastoma(s) and BCC show consistent expression of CK6hf, CK14, and CK17; variable expression of CK15 and CK19; and absence of hair keratins. This indicates a differentiation toward the outer root sheath epithelium or the companion layer and not toward the inner root sheath, matrix, or cortex.

Expression of desmosomal proteins in squamous cell carcinomas of the skin

Background:  Desmosomal proteins are well established markers of epithelial differentiation. Down‐regulation of desmosomal proteins has been suggested to be a sign of reduced adhesiveness in metastasizing cells.

Prodynorphin opioid peptides in small somatosensory primary afferents of guinea pig

By the use of light microscopic immunohistochemistry it was shown that a significant population of small primary sensory afferents of guinea pig contains immunoreactivities to antisera directed against prodynorphin-opioid peptides, whereas immunoreactivities to antisera directed against opioid peptides exclusively contained in proenkephalin were absent. Immunoreactivities to antisera against different prodynorphin-opioid peptides were seen in small ganglionic cells and in small diameter fibers of spinal and trigeminal ganglia, of dorsal roots, of somatic peripheral nerve trunks and in cutaneous sensory nerves. There was evidence for colocalization of different prodynorphin-opioid peptides. High-performance liquid chromatography and the mouse vas deferens assay revealed opioid-active material (22.7 pmol Met-enkephalin equivalents per gram wet weight) in extracts of somatic peripheral nerves. The results indicate for the first time that opioid peptides derived from prodynorphin are peripheral and central neurotransmitter candidates of small primary somatosensory afferents.

Birt-Hogg-Dube syndrome and Hornstein-Knickenberg syndrome are the same. different sectioning technique as the cause of different histology

The auiosomal dominant inherited syndromes of Horornstein and Knickenberg (HKS). and Birt, Hogg and Dubé (BHDS) are both characterized clinically by the overall spread of multiple flesh coloured papules of the skin. However, it is a mailer of debate il cnlonic neoplasms ladenomas as well as adenocarcinomas) are associated findings in the HKS or rather in the BHDS. Furthermore, histological differences are said to exist between the skin lesions in the two syndromes: whereas perifollicular fibromas were described m the HKS, fibroiolliculomas and trichodiscomas were found in the BHDS. In the present study, we report on a father and his daughter in whom we initially diagnosed a BHDS. We then examined a greater number of the papular lesions in histologic sections cut vertically as well as horizontally to the epidermis. Our results indicate that the histologic differences between the skin lesions in the two syndromes are artificial ones, caused by interpretation of different sectioning planes, and that consequently HKS and BHDS are the same. Therefore, it is necessary to look for colonic polyps in the syndrome in question, regardless if one prefers the name HKS or BHDS for it.

Merkel cells are integral constituents of desmoplastic trichoepithelioma: an immunohistochemical and electron microscopic study.

The incidence of Merkel cells has previously been investigated in a number of inflammatory and tumorous lesions of the skin. Special attention was given to tumors with follicular differentiation. In the present study we examined the localization of Merkel cells in another adnexal tumor, the desmoplastic trichoepithelioma (n= 15), as well as in its main differential diagnosis, the morpheiform basal‐cell carcinoma (n=30). Using immunohistochemical methods, we found Merkel cells as a stable constituent in desmoplastic trichoepitheliomas, but failed to detect them in morpheiform basal‐cell carcinomas. These findings might therefore be an important tool in the sometimes very difficult but clinically imperative distinction between these two conditions. Furthermore, our study may be of interest in the discussion about the origin of desmoplastic trichoepitheliomas. High numbers of Merkel cells in desmoplastic trichoepitheliomas indicate a bulge‐derived origin of this adnexal tumor, since high numbers of Merkel cells, especially in the bulge, were recently discovered. Although the significance of Merkel cell hyperplasia in desmoplastic trichoepithelioma is not presently understood, a regulatory role of the Merkel cell in growth and development of this adnexal tumor is suggested.