Expression of CD31/PECAM-1 (platelet endothelial cell adhesion molecule 1) by blastic plasmacytoid dendritic cell neoplasms.

IMPORTANCE: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare malignant neoplasm with cutaneous manifestations and a rapidly progressive clinical course. The diagnosis relies on characteristic clinicopathologic and immunopathologic features. However, the overlap of immunophenotypic features with other cancers, as well as newly discovered interpersonal and intrapersonal phenotypic variations, renders the identification of BPDCN challenging. A greater understanding of the proteins expressed by BPDCN might facilitate its recognition and provide insights into its clinical behavior. OBSERVATIONS: In 7 of 9 patients at 4 tertiary care institutions, immunohistochemical analysis demonstrated strong CD31/PECAM-1 (platelet endothelial cell adhesion molecule 1) expression by neoplastic cells. Combined with similar findings observed in 1 former patient, 8 of 10 cases of BPDCN were CD31/PECAM-1 positive. CONCLUSIONS AND RELEVANCE: Expression of CD31/PECAM-1 by BPDCN adds new information about the antigenic profile of this unusual neoplasm. CD31/PECAM-1 influences multiple cell functions including adhesion, apoptosis, coagulation, host response, and protein synthesis that might affect clinical features of BPDCN such as hemorrhage, aggressive tumor growth, and resistance to therapy. Therefore, the potential role of this molecule in the tumor formation and progression of BPDCN warrants additional exploration.

Beyond skin deep: thoracic manifestations of systemic disorders affecting the skin.

A variety of systemic disorders--infections, noninfectious inflammatory diseases, collagen vascular diseases, hereditary diseases, and acquired immune deficiency diseases--may affect both the skin and the lung. The findings in one organ system can help establish the diagnosis or limit the differential diagnosis. Cutaneous manifestations of many conditions (eg, Kaposi sarcoma) precede thoracic manifestations and sometimes have prognostic implications for respiratory disease; in other conditions (eg, organizing pneumonia in polymyositis and dermatomyositis), thoracic manifestations precede cutaneous ones. When skin and thoracic manifestations develop simultaneously, as occurs in the acute form of sarcoidosis known as Löfgren syndrome, the diagnosis is often readily established. Familiarity with the appearances of skin lesions that are commonly associated with systemic lung disease, especially those that are disease specific, may allow the radiologist to pinpoint a diagnosis even when thoracic imaging findings are nonspecific.

Microsatellite instability and alterations of mismatch repair protein expression in choroidal melanomas.

OBJECTIVES: To examine choroidal melanomas for genomic instability, manifested by microsatellite instability (MSI) and mismatch repair (MMR) protein alterations, and to determine the association of these alterations with selected clinicopathological features of the tumors. METHODS: Polymerase chain reaction-based microsatellite assays were applied to analyze 57 cases of choroidal melanomas using 11 microsatellite markers at 5 chromosomal regions: 1p, 2p, 4q, 9p, and 17p. Immunoperoxidase staining methods and mouse monoclonal antibodies were used to investigate the expression patterns of MMR proteins. RESULTS: Microsatellite instability was found at the 1p, 9p, and 17p regions in these lesions with an overall prevalence of 35% (20/57). The frequency of MSI ranged from 9% (1/11) to 27% (3/11), ie, low-level MSI (MSI-L). The instability was most commonly found at the 1p region (D1S2734, 55%; D1S2832, 40%; and D1S233, 20%). Two MSI banding patterns, band shifts and the appearance of additional bands, were found in 10% and 90% of the unstable lesions, respectively. The average percentages of hMLH1 and hMSH2 positively stained cells were insignificantly reduced in the unstable lesions (81.7 +/- 9.3 and 76.7 +/- 16.7) as compared with the stable lesions (84.1 +/- 15.5 and 78.6 +/- 19.6; P = .62 and 0.74 for hMLH1 and hMSH2, respectively). There was no significant difference in survival between the 2 groups; however, relative to the stable subset, the unstable tumors showed a trend (P<.10) toward occurring at a younger age and having tumor cells in vascular lakes. CONCLUSIONS: The presence of MSI-L in some choroidal melanomas defines a novel genetic subset of these tumors and suggests that MSI (genomic instability) may play a role in their molecular pathogenesis. Elucidation of the underlying mechanisms for MSI will require further investigation. CLINICAL RELEVANCE: Detection of the MSI-L pattern might prove to be useful as an adjunct to the conventional diagnosis of choroidal melanomas. Larger series are needed to determine whether any of the correlative trends noted in this study will achieve statistical significance. To the best of our knowledge, this study is the first to define both the MSI and MMR protein expression features of choroidal melanomas.

Apoptosis and melanoma: molecular mechanisms.

Melanoma cells can undergo self-destruction via programmed cell death, i.e. apoptosis. In these tumours, the molecular components of apoptosis include positive (apoptotic) and negative (anti-apoptotic) regulators. The former include p53, Bid, Noxa, PUMA, Bax, TNF, TRAIL, Fas/FasL, PITSLRE, interferons, and c-KIT/SCF. The latter include Bcl-2, Bcl-X(L), Mcl-1, NF-(K)B, survivin, livin, and ML-IAP. Alternatively, some molecules such as TRAF-2, c-Myc, endothelins, and integrins may have either pro- or anti-apoptotic effects. Some of these molecules are of potential therapeutic use, such as: (1) p53, which influences resistance to chemotherapy; (2) Mcl-1 and Bcl-X(L), which can override apoptosis; (3) TRAIL, which has selective fatal effects on tumour cells; (4) NF-(K)B, which when downregulated sensitizes cells to TRAIL and TNF; (5) the PITSLRE kinases, whose alteration appears to result in Fas resistance; (6) interferons, which sensitize cells to other factors; and (7) survivin and other IAPs that inhibit apoptosis. This review summarizes the state of current knowledge about the key molecular components and mechanisms of apoptosis in melanoma, discusses potential therapeutic ramifications, and provides directions for future research.