Fine needle aspiration cytology of a low grade myxoid renal epithelial neoplasm: a case report.

BACKGROUND: Recently, several case reports have described a rare but distinct subtype of renal tumor, referred to as a "low grade renal epithelial neoplasm," that appears to have a better prognosis than conventional renal cell carcinoma does. This report describes the cytologic features of this tumor as determined by fine needle aspiration (FNA) biopsy. CASE: A 53-year-old woman with a history of lymphoma had a renal mass incidentally discovered on an abdominal computed tomographic scan performed for lymphoma restaging. Results of an FNA biopsy showed relatively uniform, medium-sized tumor cells with moderate amounts of finely vacuolated or wispy cytoplasm and indistinct cell borders. The nuclei were primarily round with coarse chromatin and had prominent nucleoli. In the cell block preparation, the tumor cells showed a tubular architecture and an abundant myxoid matrix. The patient underwent a partial nephrectomy. The tumor was classified as a low grade myxoid renal epithelial tumor. CONCLUSION: This unusual kidney tumor appears to have distinctive cytomorphologic features, including a uniform population of epithelial cells with round nuclei, an abundant myxoid matrix and tubular architecture.

Expression of human 8-oxoguanine DNA glycosylase (hOGG1) in follicular lymphoma.

The human homologue of the yeast DNA repair enzyme 8-oxoguanine DNA glycosylase (hOGG1) repairs oxidatively damaged guanosine nucleotides in DNA. This enzyme is highly expressed in reactive germinal centers, where lymphoid cells are under oxidative stress, and has been thought to protect lymphocytes from mutation. As a first step to investigate the role of hOGG1 in lymphomagenesis, we evaluated hOGG1 expression in follicular lymphoma. Immunohistochemistry was performed on formalin-fixed paraffin-embedded tissue of 28 follicular lymphoma cases (16 grade 1, seven grade 2, and five grade 3) to evaluate the expression of hOGG1 in neoplastic follicles. Reactive germinal centers of non-neoplastic tonsil and lymph node tissue were also examined. Fluorescent-in-situ hybridization (FISH) was performed using a DNA probe from BAC clone RP11-266J6 corresponding to 3p25, where the hOGG1 gene resides, to evaluate for the presence or absence of a deletion. In reactive germinal centers, the majority of centroblasts and centrocytes were positive for hOGG1. In contrast, the majority (21 of 28 or 75%) of follicular lymphoma cases showed absent/minimal expression of hOGG1. Only four of 28 (14%) follicular lymphoma cases revealed the same levels of hOGG1 expression as reactive germinal centers. There was no correlation between hOGG1 expression and histologic grade. None of the 16 cases evaluated by FISH showed a deletion of hOGG1. Furthermore, absent/minimal hOGG1 expression was observed in four of six Bcl-2-negative follicular lymphoma cases. Our findings suggest that absent/minimal hOGG1 expression occurs in the majority of follicular lymphomas. The downregulation of hOGG1 does not appear to be due to a deletion of the hOGG1 locus. Additionally, finding absent/minimal hOGG1 expression in a subset of Bcl-2-negative follicular lymphomas suggests that hOGG1 may have utility in diagnosing Bcl-2-negative follicular lymphomas.

Reduced expression of cytokeratin 20 in colorectal carcinomas with high levels of microsatellite instability.

High levels of microsatellite instability (MSI-H) result from abnormal nucleotide mismatch repair in a subset of sporadic colorectal carcinomas (CRC) and in most CRC of hereditary non-polyposis colorectal cancer syndrome. CRC with MSI-H have distinctive clinical-pathologic features, but the immunophenotype has not been studied extensively. We evaluated immunohistochemical expression of cytokeratin 7 (CK7), cytokeratin 20 (CK20), and pancytokeratin (panCK) in 44 CRC from 22 paired MSI-H and microsatellite-stable (MSS) cases matched for clinical-pathologic characteristics. The mean percentage of CK20+ tumor cells was 84 +/- 6% in MSS CRC but only 37 +/- 8% in MSI-H CRC (P = 0.0007). Thirty-two percent (7/22, 95% confidence interval 14-55%) of MSI-H CRC were CK20-, as contrasted with 9% (2/22, 95% CI 1-29%, P = 0.13) of MSS CRC. CK20 expression was inversely correlated with levels of MSI (rs = -0.45, P = 0.006). CK7+ was infrequent (16%, 7/44, 95% CI 7-30%) and panCK+ was universal, with no significant differences between MSI-H and MSS CRC. Our study shows that decreased or even absent CK20 expression is a phenotypic characteristic of MSI-H CRC and that MSI-H explains much of the subset of CRC that lack CK20 expression. Our results also indicate that regulation of CK20 gene expression involves molecular pathways that are altered by MSI-H.

Fine-needle aspiration of adult rhabdomyoma: a case report with review of the literature.

The cytologic features of adult rhabdomyoma, a rare benign tumor of skeletal muscle origin, have been infrequently reported in the literature. We present here a case of a rhabdomyoma involving the floor of the mouth of a 78-year-old man initially diagnosed by fine-needle aspiration cytology. Cytologic features seen on Papanicolaou-stained smear preparation included cohesive clusters of skeletal muscle cells having abundant eosinophilic cytoplasm and often peripherally located nuclei. Although cross-striations and elongated intracytoplasmic inclusions were not identified in the smears, they were noted in the cell block preparation of the aspirated specimen and in the touch preparation and histologic sections of the surgically resected specimen. The cytologic differential diagnosis of this tumor is discussed.

Cryptococcal infection of the larynx simulating laryngeal carcinoma.

Cryptococcus neoformans is an encapsulated yeast that can cause primary pulmonary infections or disseminate and cause infections of the central nervous system, meninges, skin, and bone in the immunocompromised host. We present here an unusual case of an immunocompetent patient who had laryngitis due to C. neoformans that mimicked a laryngeal carcinoma on clinical examination and imaging studies.