Analysis of ret/PTC gene rearrangements refines the fine needle aspiration diagnosis of thyroid cancer.

Papillary carcinoma (PC) represents the most common malignancy of the thyroid gland. Therefore, the assessment of fine needle aspiration biopsies of thyroid nodules rests heavily on the identification of nuclear features of PC. The ret/PTC oncogene, formed by several gene rearrangements, is specific for PC among thyroid tumors. In this study we examined thyroid aspirates for the presence of ret/PTC gene rearrangements by RT-PCR and Southern hybridization. We prospectively collected thyroid aspirates in Cytolyt solution and prepared slides for cytological examination using the ThinPrep method. All remaining material was then used for nucleic acid extraction with subsequent RT-PCR for the housekeeping gene PGK-1 to ensure ribonucleic acid integrity, for thyroglobulin to ensure the presence of follicular epithelial cells, and for the three most common ret/PTC gene rearrangements (ret/PTC-1, -2, and -3). The results of the first 73 cases with surgical follow-up were correlated with the cytological diagnosis and final histopathology. ret/PTC gene rearrangements were detected in 17 of 33 samples (52%) that were PC on histopathology; the presence of gene rearrangements was confirmed by molecular analysis of corresponding surgically resected frozen tissue. There were no false positives. The identification of ret/PTC gene rearrangements refined the diagnosis of PC in 9 of 15 specimens (60%) that would otherwise have been considered indeterminate and in 2 of 6 that were considered insufficient for cytological diagnosis. The results indicate that RT-PCR for ret/PTC is a specific marker that can be applied to fine needle aspiration biopsies and improves the diagnosis of malignancy when used as an adjunct to traditional cytology.

Cytologic diagnosis of extravesical malacoplakia.

Malacoplakia, a rare form of chronic granulomatous inflammation, most frequently involves the urinary tract of middle-aged women. The disease represents an unusual inflammatory response to bacteria, most commonly Escherichia coli, and probably reflects some dysfunction in the immune system of the host. We describe two cases of malacoplakia involving in one patient the vagina and in the other the perianal subcutaneous tissue and lung. In both cases, the diagnosis was made concurrently by cytology and histologic examination of tissue sections. This, in turn, led to the institution of appropriate therapy with complete resolution of the disease. In smears, the characteristic von Hansemann histiocytes are larger than alveolar macrophages. They have a reticulated granular cytoplasm that is caused by excessive accumulation of lysosomal bodies, some of which upon mineralization give rise to the pathognomonic Michaelis-Gutmann body. The latter, which is usually intracellular, can be distinguished readily from psammoma bodies and should not be confused with yeasts.

Fine-needle aspiration biopsy of the thyroid gland: results of a five-year experience and discussion of its clinical limitations.

The results of a five-year experience with fine-needle thyroid aspiration cytology are reported to assess the value, accuracy and limitations of this biopsy procedure. The cytologic diagnoses on 1,465 thyroid aspirates are listed, and correlation of cytology with histology on 207 cases undergoing surgery is reported. The incidence of malignancy among the atypical and malignant cytology aspirates with histologic confirmed diagnosis was 65% (28/43) while a false negative rate of 11.5% (15/131) was found. Fine-needle aspiration biopsy is a safe and useful procedure with an acceptable accuracy rate that complements other investigations in the screening of patients for thyroid surgery.