Glomerular deposition of immune complexes as a first manifestation of malignant melanoma - a case report.

INTRODUCTION: Immune complex (IC) deposition in renal tissue is considered as a possible tumor marker. This raised the hypothesis that some tumor markers might be related to the patient prognosis, with emphasis in the possibility to detect them in tissue sample, not only in blood. We report a patient with membranous glomerulonephritis (MGN) and tumoral IC deposition that were detected previous to the diagnosis of melanoma. CASE REPORT: A 55-year-old male was admitted to our department with symptoms of renal disease; a kidney biopsy was performed and the diagnosis was phase II MGN. A few months later he returned to the hospital with ascites, dyspnea, anorexia, and macular erythematous skin lesions in the body. A new urinalysis showed proteinuria, hematuria, and leukocyturia; the chest X-ray showed a lung nodule; and a brain CT scan revealed a frontal nodular lesion, suggesting metastasis. The brain biopsy suggested the diagnosis of metastatic melanoma and a posterior kidney immunohistochemistry study with S-100 and HMB-45 antibodies showed glomerular and tubular positivity for these markers. CONCLUSIONS: MGN and deposition of tumoral IC as a first manifestation of melanoma has not been previously reported. This case reinforces the importance of a clinical evolution focused on the diagnosis of a hidden cancer in patients with MGN. Oncologists should also be aware of the potential occurrence of glomerular lesion in their patients and that could be important during tumor therapy.

pRB detection as a common event in human retinoblastomas: an immunohistochemical study.

Approximately 30% of the cases of retinoblastoma (RB), the childhood eye cancer, are inherited and are manifested by unilateral or bilateral tumor. In sporadic tumors, accounting for 70% of cases, only one eye is affected. RB has three histological features: undifferentiated anaplastic cells, retinoblast pattern, and differentiated pattern characterized by Flexner Wintersteiner rosettes (FWR). Currently, results concerning phosphoprotein RB (pRB) expression in RB tumors are contradictory. In this study we detected pRB immunohistochemically in 10 tumors from bilateral or unilateral RBs, which did not show gross chromosomal alterations in cytogenetic studies. Interestingly, pRB was undetectable in only one tumor where we found distinct histological features. Our results suggest that pRB immunopositivity may be common in these tumors. However, it does not rule out the possibility that pRB is functionally inactive in some cases. This may be due to the protein being present in phosphorylated form or being altered by point mutations not affecting its expression. Another possibility is that mechanisms other than RB1 gene changes may lead to retinoblastoma because not all cases of retinoblastoma show gene alterations. Together these findings may be useful in understanding the molecular mechanisms associated with this type of pediatric tumor.

MUC1 cytoplasmic tail detection using CT33 polyclonal and CT2 monoclonal antibodies in breast and colorectal tissue.

UNLABELLED: The immunohistochemical detection (IHC) of MUC1-CT employing a polyclonal antibody (CT33) in relation to CT2 monoclonal antibody (MAb) was analyzed. Western blot (WB) was used to determine the molecular mass of CT. MATERIALS AND METHODS: We studied 163 breast and 89 colorectal cancer specimens, 10 breast and 14 colorectal benign conditions, and 12 breast and 20 colorectal normal samples. From each tumor sample, subcellular fractions were obtained and analyzed by SDS-PAGE and WB. A nonparametric statistical analysis was employed; data were standardized and a Kendall-Tau correlation was applied. RESULTS: By IHC, 146/163 (90%) and 151/163 (93%) of breast cancer were positive with CT33 and CT2, respectively; a statistically significant correlation was obtained (t=0.5199). Seven out of ten (70%) benign breast specimens were positive with CT33 while all samples stained with CT2; in normal breast sample tissues, all were positive with both Abs. In colorectal cancer samples, both antibodies stained 47/89 (53%) samples; CT2 reacted in 13/14 (93%) of benign samples while CT33 showed a positive reaction in 9/14 (64%) of benign specimens. In normal samples, CT2 showed staining in 17/20 (85%) of samples and CT33 was reactive in 12/20 (60%). By WB, in breast and colorectal cancer samples, similar results were obtained with both antibodies: a main band at about 30kDa which represents the smaller subunit. CONCLUSION: CT33 polyclonal antibody has demonstrated its efficacy to detect MUC1 in breast and colorectal cancer tissues with similar reactivity to CT2. It is worthwhile to affirm that CT33 is a good indicator of MUC1 expression.