Detection of melanin-mediated false-positive for BaxΔ2 immunohistochemical staining in human skin tissues

BaxΔ2 is a pro-apoptotic isoform of the Bax family. We have previously shown that BaxΔ2 protein expression is low in most healthy human tissues with the protein mainly scattered in the connective tissues. Surprisingly, in skin tissue, the BaxΔ2-positive staining was strikingly strong, especially in the basal layer of the epidermis. It has been documented that melanin in the basal cells displays a brown color that could give false-positive staining in the commonly used DAB-based (3-3’-diaminobenzidine) immunostaining. To avoid the false-positive staining from DAB-melanin, we performed immunofluorescent staining on the same set of tissues which were positive for BaxΔ2 in the DAB immunostaining. The results from co-immunofluorescent staining of BaxΔ2 and a basal cell marker CK-14 showed that the previously detected DAB-stained BaxΔ2-positive epidermal cells were CK-14 positive but BaxΔ2 negative. Consistent with our previous finding, the BaxΔ2-positive cells in the dermis connective tissues are positive in both DAB-based and fluorescence-based immunostainings. These data indicate that the DAB-stained BaxΔ2 positive cells in the basal layer of skin tissue are false-positive due to a misinterpretation of the melanin color, but the dermal connective tissue still presents real BaxΔ2 positive staining.

Pathological changes of immunized mice with Trichophyton mentagrophyte lyophilized antigen

The study was carried to investigate the pathological effect of lyophilized antigen of Trichophyton mentagrophytes in mice. Fifty mice were divided into three groups. The first group 20 mice were immunized subcutaneous (s/c) with 0.5 ml of T.mentagrophyte antigen 20 µgm/ml, by two doses, 14 day intervals, between them. The second group 20 mice and third group 10 mice considered as positive and negative control groups respectively. After 30 days post immunization first and second groups were challenged intradermal I/d. with 0.1 ml of fungal suspension contain (1×107 ml) of viable virulence T.mentagrophyte while the third group injected intraperitoneally I/P. with 0.5 ml of sterile phosphate buffer saline. All mice of the first and second groups were sacrificed at (5, 14, 30 and 60) days post challenge for gross and histopathological examination. Histopathologically the second group showed epidermal hyperkeratosis with appearance of crust lesions seen with abscess formation especially in early stage of lesion, while the main feature of advance cases were characterized by folliculitis with fungal hyphae invasion in all epidermal and dermal layers together with eosinophilic infiltration. Mild pathological changes were seen in the 1st immunized group characterized by infiltration of mononuclear cells mainly macrophages in dermal connective tissue with dense proliferation of collagenous fibers , appearance of young fibroblasts together with cellular hypodermal infiltration of eosinophil no evidence of clear follicular lesions were seen. Lyophilized antigen of T.mentagrophyte can be considered as an effective immunogen for protecting mice against T.mentagrophyte infection and it is synchronized with its dose.

A rare case of carcinoma cuniculatum of the penis in a 55-year-old

Carcinoma cuniculatum of the penis is an extremely rare variant ofsquamous cell carcinoma characterized by an endophytic deeplybranching and burrowing growth pattern. One documented caseseries demonstrated afflicted patients ranging in age from 73-83years with the tumour located on the glans penis, coronal sulcusor foreskin. We report a case of a 55-year-old with disease locatedon the ventral aspect of the shaft of the penis. The tumour wasinvasive into the deep dermal connective tissue, comparativelysuperficial to all previous documented cases. He subsequentlyunderwent a partial penectomy. The case is discussed with a briefreview of the literature.