Colonization of the colon and rectum by intestinal spirochetes is detected for the first time in Brazil in 4 of 282 (1.41%) patients who had undergone sigmoidoscopy and/or colonoscopy with a histopathological diagnosis of chronic non specific-colitis. This frequency is probably understimated, since surgically obtained specimens were not considered in the present study. Histopathological diagnosis was performed using routine stains like hematoxylin-eosin which showed the typical, of 3-µm thick hematoxyphilic fringe on the brush border of the surface epithelium, and by silver stains like the Warthin-Starry stain. Immunohistochemical procedures using two, polyclonal, primary antibodies, one against Treponema pallidum and the other against Leptospira interrogans serovar copenhageni serogroup Icterohaemorrhagiae cross-reacted with spirochetal antigen/s producing a marked contrast of the fringe over the colonic epithelium, preserving the spiral-shaped morphology of the parasite. In one case with marked diarrhea, immunohistochemistry detected spirochetal antigen/s within a cell in an intestinal crypt, thus demonstrating that the infection can be more widely disseminated than suspected using routine stains. Immunohistochemical procedures, thus, greatly facilitate the histological diagnosis of intestinal spirochetosis and may contribute to a better understanding of the pathogenesis of the disease. Transmission and scanning electron microscopy performed in one case showed that the spirochete closely resembled the species designated as Brachyspira aalborgi.

There are 36 cases of complex poroid tumors with folliculosebaceous and apocrine differentiation reported in the literature. The authors evaluated 111 poroid tumors including 63 typical eccrine poromas and 48 poroid tumors with folliculosebaceous elements. Folliculosebaceous poroid tumors (FSPT) had basaloid and squamous cells (100%), ducts with steatocystoma-like cuticles and holocrine secretions (89.6%), infundibular follicular structures (66.7%), and entrapped sebocytes (56.3%). No definite apocrine decapitation secretions in FSPT were found. Immunohistochemistry was strongly positive for CK903 and focally positive for CAM5.2, epithelial membrane antigen, and carcinoembryonic antigen. No loss of MLH-1, MSH-2, or MSH-6 mismatch repair proteins was found. FSPT had distinctive features that differentiate them from eccrine poromas including the frequent head and neck locations (62.5% vs. 20.6%, P < 0.01), squamous cytology (100% vs. 1.6%, P < 0.01), more prominent cytoplasmic vacuolization (score 1.4/4.0 vs. 0.3/4.0, P < 0.01), presence of infundibular follicular structures (score 1.2/4.0 vs. 0.03/4.0, P < 0.01), presence of ducts with steatocystoma-like cuticles (89.6% vs. 0.0%, P < 0.01), and less stromal hyalinization (score 1.0/4.0 vs. 2.5/4.0, P < 0.01). The authors propose that FSPT are distinctive benign tumors originating from the sebaceous gland duct and are therefore best categorized as holocrine poroma.

Adult worm antigen (AWA) and soluble egg antigen (SEA) were localized ultrastructurally by immunoelectron microscopy using two monoclonal antibodies in the glomeruli of hamsters infected with Schistosoma mansoni cercariae or injected with S. mansoni eggs. AWA was detected in all cercaria-infected groups from the 30th day on and was present mainly in cytoplasm of mesangial cells, mesangial matrix, and glomerular basement membrane, either as isolated gold particles or in small electron-dense deposits of probable immune origin. AWA was encountered also on the inner side of the glomerular basal membrane, close to endothelial cells, and in the foot processes of the glomerular epithelial cells. SEA was detected at similar sites, apparently in lesser amounts, in uninfected hamsters inoculated with S. mansoni eggs into the jugular vein. Schistosomal antigens are apparently processed mainly by mesangial cells which are considered to be critical in the pathogenesis of S. mansoni associated glomerulopathy. Mesangioproliferative glomerulonephritis, immunoglobulin (IgG and IgM), and C₃ deposits were observed in hamsters in which AWA and SEA were visualized. During early phases of the infection and in hamsters in which granulomatous pneumonitis was induced by S. mansoni eggs, glomeruli were unchanged or showed a slight mesangial proliferation. Our findings suggests that egg antigens also contribute to the pathogenesis of experimental glomerulopathy in the hamster.

Although rare, congenital malignant melanoma (CMM) should be considered in the differential diagnosis of congenital skin lesions. We report a case of CMM in a 4-month-old infant presenting with an enlarging scalp mass, initially thought to be a hemangioma. Incisional biopsy of the lesion showed a compound congenital nevus with atypical cells suggestive of a proliferative nodule versus malignancy on histopathology. Subsequent excisional biopsy revealed malignant melanoma, and further workup confirmed extensive disease with distant metastases. Cytogenetic analysis of both the tumor sites showed highly abnormal karyotypes including pseudotetraploidy, telomere associations, and evidence of gene amplification, all consistent with malignancy. Fluorescence in situ hybridization demonstrated amplification of the MYC gene, with no copy number changes in CDKN2A (INK4/ARF), PTEN, or Cyclin D1. Our report details the cytogenetic and molecular studies of CMM, which provide insight into the biologic behavior of the lesions and may confirm diagnosis when histopathology is not determinant.

The authors studied the distribution of Paracoccidioides brasiliensis antigen(s) in human skin and oral mucosa. In biopsies obtained from untreated patients showing the chronic form of the disease, the authors demonstrated the P. brasiliensis antigen using two polyclonal immune sera raised in rabbits, one against the exoantigens of P. brasiliensis and the other against a 43-kDa glycoprotein. Langerhans' cells were detected through double immunolabeling using an anti-S 100 protein monoclonal antibody. Double labeling immunohistochemistry showed that both of the immune sera labeled the yeast cells in the center of the granuloma and those transmigrating through the epithelial layer equally well. Granulomas exhibited the P. brasiliensis antigen permeating cells, mainly at the periphery of the granulomatous inflammation. The P. brasiliensis antigen(s) accumulated in the macrophages but not in the Langerhans' cells. P. brasiliensis antigens, detected by antiserum against parasite exoantigens, were also deposited between basal keratinocytes, but not in the granular cells, in 47% of the biopsies. P. brasiliensis antigens, as assessed by immunoelectron microscopic techniques, are present in the cytoplasm of the yeast cells in the host tissues. Antigens are transported to the cell membrane and later excreted through the cell wall. Antigenic deposits are also seen at the fungus-host interface. Int J Surg Pathol 3(3):181-188, 1996