[Psoriatic onycho-pachydermo- periostitis]. / Psoriatische Onycho-Pachydermo-Periostitis.

We report about a patient with a 2 year history of palmo-plantar psoriasis and psoriatic involvement of the nails. Within six months he developed a psoriatic onychodystrophy and painful swellings of the toes and fingers. X-rays revealed acral lamellar periostitis. The case of this patient represents a rare variety of psoriatic arthritis: The psoriatic onycho-pachydermo-periostitis. After a 6 week therapy with methotrexate (15mg per week) the nails began to grow regularly. Therefore, in cases of psoriasis with unusual symptoms of psoriatic arthritis the psoriatic onycho-pachydermo-periostitis should be included in differential diagnosis and therapy.

Microsatellite instability in malignant melanomas.

Microsatellite instability (MSI) is caused by deficient DNA mismatch repair, and results in a "mutator" phenotype. Recent studies have produced contradictory results about the frequency and significance of MSI in malignant melanomas. In this study, we therefore determined the time of onset and relative frequency of MSI during the progression of melanocytic tumours, including benign melanocytic naevi. We examined 7 different microsatellite loci in 9 melanocytic naevi, 25 primary malignant melanomas and 8 melanoma metastases. None of the melanocytic naevi showed MSI. In contrast, moderate frequency of MSI in 1/12 (8%) was detected in thin melanomas of <0.75 mm vertical thickness and in 1/8 (12%) of those with a thickness >0.75 mm and < 1.5 mm. The rate of MSI was increased in tumours thicker than 1.5 mm (2/5) and in melanoma metastases, with over 25% (2/8) of the lesions investigated. We conclude that MSI occurs in a considerable subset of malignant melanomas and that there is a pattern consistent with increasing frequency of MSI with progression of melanocytic tumours.

Assessment of microsatellite instability and loss of heterozygosity in sporadic keratoacanthomas.

Variations in the length of simple repetitive tandem repeats (microsatellite instability, MIN) between constitutive and tumour DNA, which is characteristic of tumours in patients affected with hereditary nonpolyposis colon cancer (HNPCC), have been found to be very important in the carcinogenesis of a variety of human neoplasms. Recently, MIN has been found in sebaceous and colorectal tumours as well as in keratoacanthomas of Muir-Torre syndrome. In order to elucidate the significance of both MIN and loss of heterozygosity (LOH) in the pathogenesis of sporadic keratoacanthomas, the presence of MIN and LOH at five loci [chromosome 5q21 (D5S346, APC), 9p21 (D9S171, p16), 10pter (D10S89, Mfd28), 11p (D11S904) and 17p12 (D17S520, p53)] was evaluated. MIN was found at only one locus (p53) in 1 of 12 keratoacanthomas and no evidence for the presence of LOH could be detected. Our results suggest that, in contrast to keratoacanthomas associated with Muir-Torre syndrome, neither MIN nor LOH appear to be significant in the induction of sporadic keratoacanthomas.

Loss of expression or mutations in the p73 tumour suppressor gene are not involved in the pathogenesis of malignant melanomas.

Recently p73, a novel p53 homologous tumour suppressor gene, has been cloned and mapped to chromosome 1p36. Like p53, important functions of p73 in controlling the cell cycle and programmed cell death have been described. Loss of p73 has been demonstrated in neuroblastomas and its involvement in tumorigenesis has been suggested to occur in other neuroectodermal cancers. Since genetic alterations at the tumour suppressor locus 1p36 have been also identified in malignant melanomas, we investigated the expression of p73 in a panel of nine different human melanoma cell lines, 17 melanocytic naevi, 17 primary malignant melanomas and 20 metastases by reverse transcriptase polymerase chain reaction (PCR) and Southern blotting. We observed significant p73 mRNA expression in all the cell lines and tissue specimens except one benign melanocytic naevus and one melanoma metastasis. Sequencing the PCR fragments of nine melanoma cell lines derived from primary tumours and five metastases over the entire p73 DNA binding domain revealed wild-type sequences in all cases. In summary, we conclude that loss of p73 mRNA expression or mutations in the p73 DNA binding domain do not represent common genetic events involved in the pathogenesis of malignant melanomas.