Peptidylarginine deiminases (PADs) catalyse a post-translational modification of proteins through the conversion of arginine residues into citrullines. The existence of four isoforms of PAD (types I, II, III and IV) encoded by four different genes, which are distinct in their substrate specificities and tissue-specific expression, was reported in rodents. In the present study, starting from epidermis polyadenylated RNA, we cloned by reverse transcriptase-PCR a full-length cDNA encoding human PAD type I. The cDNA was 2711 bp in length and encoded a 663-amino-acid sequence. The predicted protein shares 75% identity with the rat PAD type I sequence, but displays only 50-57% identity with the three other known human isoforms. We have described the organization of the human PAD type I gene on chromosome 1p36. A recombinant PAD type I was produced in Escherichia coli and shown to be enzymically active. Human PAD type I mRNAs were detected by reverse transcriptase-PCR not only in the epidermis, but also in various organs, including prostate, testis, placenta, spleen and thymus. In human epidermis extracts analysed by Western blotting, PAD type I was detected as a 70 kDa polypeptide, in agreement with its predicted molecular mass. As shown by immunohistochemistry, the enzyme was expressed in all the living layers of human epidermis, with the labelling being increased in the granular layer. This is the first description of the human PAD type I gene and the first demonstration of its expression in epidermis.

This report summarizes a cumulative 4-year experience in polymerase chain reaction (PCR) analysis of immunoglobin heavy chain (IgH) and TcR-␥ chain gene rearrangements in 525 cases of lymphoproliferative disorders. Because the sensitivity of the PCR methodology was found to be tissue dependent, in the study of the presence of clonal cell population in tissues containing a small number of polyclonal lymphocytes, such as skin and gastrointestinal biopsy specimens, we used the multiple-PCR run approach. In this latter methodology, we repeat the PCR reaction from the same sample at least three times to confirm the reproducibility of the results. In the study of 273 cases of B-or T-cell lymphomas with characteristic immunomorphological and clinical features, a clonal IgH or TcR-␥ chain gene rearrangement was detected in approximately 80% of cases. A clonal rearrangement involving both IgH and TcR-␥ chain genes was found in 10% of cases of both B-cell and T-cell lymphomas. The study of 167 cases of nonneoplastic lymphoid tissue samples showed the presence of clonally rearranged cell populations for IgH or TcR-␥ genes in 3 and 9% of cases, respectively. We also applied PCR for the study of 85 cases of lymphoproliferations with no definite diagnosis (i.e., benign versus malignant) after immunomorphological analysis. In 65 cases (76%), the correlation of immunomorphological features with the presence (48 cases) or the absence (17 cases) of clonal lymphoid cell populations led to a definite diagnosis. In almost all these cases, the final diagnosis was found to be in agreement with the clinical course. In the 20 remaining cases (24%), no definite diagnosis could be made. We also assessed the value of PCR in detecting bcl-2/J H gene rearrangement as an additional clonal marker in the diagnosis of follicular lymphoma. Bcl-2/J H rearrangement and/or IgH gene rearrangement was found in approximately 85% (71/85) of follicular lymphoma cases studied.

Management of incompletely excised nonaggressive BCCs (nodular or superficial types) is still a matter of debate. Previously reported studies have shown recurrence in < 10% of nonaggressive incompletely excised BCCs. Our study showed that rare recurrences of these initially nonaggressive BCCs showed an aggressive component in 20% of cases. These results suggest that initially nonaggressive incompletely excised BCCs do not require re-excision except if they are located in sites with a poor prognosis.

We report the production of a new monoclonal antibody, PNL2, directed against a fixative resistant melanocyte antigen. The analysis of PNL2 immunostaining on a broad range of normal or malignant human tissues and on various melanocytic lesions revealed its high specificity. PNL2 gave a strong cytoplasmic staining of skin and oral mucosae melanocytes, and staining of granulocytes when used at high concentration. PNL2 stained all intraepidermal nevi irrespective of their histologic type, but common intradermal nevi and the dermal component of compound nevi were largely non-reactive as only scattered nevus cells in the papillary dermis were labeled. PNL2 labeled more than 70% of the neoplastic cells in all primary melanomas irrespective of their histologic type. However, PNL2 did not label desmoplastic melanomas. All metastatic melanomas were also stained but the percentage of labeled cells was occasionally lower than the primary tumor. PNL2, as anti-Melan A and HMB-45 antibodies, stained most of the clear cell sarcoma cells, and a few cells in angiomyolipomas and lymphangioleiomyomatosis. None of the other nonmelanocytic lesions tested were labeled. Proteomic approaches showed that the immunoaffinity purified PNL2-binding complexes isolated from melanoma cell lines comprise at least TAP1, Clathrin 17 and prealbumin proteins, but not the gp100 recognized by HMB-45. In conclusion, this new monoclonal antibody, PNL2, is directed against a new fixative resistant melanocyte associated antigen. This antigen is chemically resistant and thus allows immunostaining after melanin bleaching or decalcification. We also demonstrate that it is different from Melan A and from gp100, even if PNL2 and HMB-45 staining patterns are sometimes similar.

We investigated a series of 122 cases of small cell lung carcinomas and non-small cell lung carcinomas for the presence of several viruses that are known to be oncogenic in humans. Thus, viral genomes (DNA) and/or RNA transcripts and/or proteins of human papillomaviruses (HPV) 16, 18, 31, 33, 51, Epstein -Barr virus (EBV), human herpesvirus 8 (HHV-8), human cytomegalovirus (HCMV) and simian virus 40 (SV40) were investigated on tissue sections (prepared in tissue microarrays) with different techniques of immunohistochemistry and in situ hybridisation. None of the cases displayed a single positive tumour cell for all the viruses tested whatever the technique applied. Of note, in five cases of tumours with lymphoid infiltrates, we detected scattered EBV (EBER)-positive bystander lymphocytes. In three cases, a faint nuclear staining was found with the anti-latent nuclear antigen/LANA1 (HHV-8) antibody. These cases were checked by PCR with two sets of primers (orf 26 and orf 75) and remained negative for this latter virus. Taken together, our data strongly suggest that the conventional human oncogenic viruses (HPV, EBV, HCMV, HHV-8 and SV40) are unlikely to play some role in the development of lung carcinomas.

Mantle cell lymphoma (MCL) is a B cell neoplasm that most often shows a diffuse growth pattern. Two cases of MCL are reported here, both with a previous diagnosis of lymphoid hyperplasia. Morphologically, germinal centres are hyperplasic with a normal or discretely enlarged mantle zone, where foci of irregularly shaped small lymphocytes are seen. These are positive for CD20, CD5 and cyclin D1, confirming a diagnosis of in situ-like MCL. This type differs from the mantle zone pattern in that the neoplastic mantle zone is very thin and there is very little or no spread of tumour cells into interfollicular areas. To the best of our knowledge, this is the first report on such a pattern of MCL, which is important to recognise, as it can be confused with lymphoid hyperplasia.

Non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL) represent a heterogeneous group of malignant lymphoid tumors, which have distinct histological and/or biological characteristics with preferential nodal involvement. However, none of the previous studies have assessed the prevalence of common NHL and HL subtypes at each nodal site of involvement.The aim of our study was to determine the prevalence of HL and NHL subtypes depending on their nodal sites of involvement.We conducted a single-center retrospective study of 938 lymphoma cases diagnosed in the Pathology Department of Toulouse Purpan Hospital in France between 2001 and 2008, taking into account the site that corresponded to the diagnostic biopsy.The most frequent sites were cervical lymph nodes (36.8% of all cases), inguinal lymph nodes (16.4%), axillary lymph nodes (11.9%), and supraclavicular lymph nodes (11%). We found an unexpected association between intraparotid nodes and nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and between inguinal nodes and follicular lymphoma. The risk of having classical Hodgkin lymphoma (CHL) was 15 times greater in patients with mediastinal lymphoma compared to those with other sites of involvement. Regarding HL, nodal and extranodal mediastinal sites and supraclavicular nodes were more likely to be involved by nodular sclerosis Hodgkin lymphoma (NSCHL). In addition, intra-abdominal lymph nodes were more frequently involved by lymphocyte depleted Hodgkin lymphoma compared to inguinal nodes where NLPHL predominated.Our study shows that some lymph node sites have a disproportionate prevalence of specific subtypes of lymphoma. Identifying these sites may aid to diagnose and better elucidate the pathogenesis of these tumors.

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