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Anti-α-inhibin, an antibody directed against a peptide hormone, has been shown to be a useful diagnostic aid in surgical pathology material for the identification of sex cord–stromal neoplasms and recently has been described in adrenocortical carcinoma (ACC). The diagnosis of ACC versus renal cell carcinoma (RCC) may be difficult morphologically, particularly in fine-needle aspiration (FNA) material. To date, the immunohistochemical distinction of ACC from RCC is based on a panel of antibodies that include vimentin, cytokeratins, and epithelial membrane antigen. However, the reliability of this panel is weakened by inconsistent staining patterns. Archival formalin fixed, paraffin embedded cell block sections from 45 FNAs of known primary and metastatic ACC and RCC as well as benign adrenocortical nodules were stained with anti-α-inhibin using an avidin-biotin procedure. All samples were microwave pretreated and a biotin block was performed to reduce the background stain due to the high endogenous biotin often present in these types of samples. All cases of ACC (n = 7; 100%) and benign adrenocortical cells (n = 15; 100%) were immunoreactive with the α-inhibin antibody, showing a diffuse cytoplasmic and granular staining pattern. The staining intensity and number of immunoreactive cells varied within each sample, with the cases of ACC having the greatest proportion of immunoreactive cells and the strongest intensity. None of the cases of RCC (n = 23; 0%) were immunoreactive with anti-α-inhibin. The morphologic distinction of ACC versus RCC in FNA material from renal, adrenal, and metastatic neoplasms is not always feasible based on cytology alone. However, due to the advent of the α-inhibin antibody, the reliable distinction of these entities now may be possible. The intense and specific immunostaining pattern for cells of adrenal origin, even in paucicellular samples, suggests potential for the widespread clinical utility of this marker by cytopathologists. Cancer (Cancer Cytopathol) 1999;87:168–72. © 1999 American Cancer Society.

The differential diagnosis of metastatic clear cell carcinoma is broad. To date, there are no specific immunohistochemical markers for renal cell carcinoma (RCC) in general use. Loss of heterozygosity (LOH) at 3p25.5, the von Hippel-Lindau (VHL) gene locus, is frequent in sporadic clear cell RCC. The authors compared LOH in primary and metastatic RCC through microdissection and the polymerase chain reaction (PCR) to evaluate these techniques as potential diagnostic tools. The authors identified 14 patients with known clear cell RCC who underwent fine-needle aspiration (FNA) evaluation of presumed metastatic lesion. Direct-visualization microdissection was performed from archival histologic glass slides of the primary neoplasm and the adjacent normal kidney parenchyma. Malignant cell clusters were microdissected from archival FNA slides of metastatic lesions. The cytology slides were previously stained with either Diff-Quik or Papanicolaou stain. This was followed by a single-step DNA extraction and PCR amplification for evaluation of LOH using polymorphic markers, D3S1038 and D3S1110, flanking the VHL gene. Thirteen of the 14 cases contained DNA suitable for PCR in both the paraffin embedded and the FNA material. Eight of the 13 cases were heterozygous (informative) for the above markers, and 6 of these showed identical allelic loss in the primary and metastatic tumor for either one or both of the markers used. The remaining two cases did not show LOH at the VHL locus with the two polymorphic markers used. DNA from archival cytologic material stained with Papanicolaou stain or Diff-Quik is reliable for PCR amplification. Visually directed microdissection in combination with PCR has the potential to be a useful technique for confirmatory identification and diagnosis of metastatic clear cell RCC in cytologic material, because a specific genetic abnormality is present in the primary tumor. As characteristic genetic abnormalities are identified in various neoplasms, the use of this technique has the potential for conclusive evaluation of metastatic disease with FNA material, when used in comparison with surgical or cytologic material from the primary tumor. The utility of this combination of techniques has the potential for the molecular diagnosis of morphologically ambiguous cell populations. Cancer (Cancer Cytopathol) 1997; 81:180-6. © 1997 American Cancer Society.

Squamous atypia in postmenopausal (PM) cervical vaginal smears (CVS) only rarely is associated with a biopsy-proven squamous intraepithelial lesion (SIL), and thus most commonly represents an atrophy-associated benign reactive change. To distinguish atypical squamous cells of undetermined significance (ASCUS) and SIL from atrophy-associated benign reactive changes, a review of atypical atrophic PM CVS was performed. Ninety CVS exhibiting an atrophic smear pattern were considered appropriate for study. Repeat smears and/or biopsy after local estrogen therapy were requested to distinguish atrophic/reactive from dysplastic changes. Generally, atrophic CVS exhibit uniform nuclear enlargement in the squamous cell population, which, using the criterion of nuclear enlargement alone, would qualify the majority of these cases to be classified as ASCUS. The nuclear enlargement associated with atrophy resolves with the local application of estrogen. Follow-up after local estrogen treatment was available for 84 of 90 patients and revealed 10 cases of SIL (12%) and 9 cases of ASCUS (11%), 6 of which were favored to be of a reactive etiology. Nuclear features most commonly noted in the cases considered to be ASCUS (nonreactive) and SIL were nuclear hyperchromasia and nuclear contour irregularities. Nuclear enlargement alone is not sufficient for diagnosing ASCUS or SIL in PM CVS. Nuclear enlargement in squamous cells is an expected normal reactive change present in PM CVS that resolves with the application of local estrogen. Nuclear hyperchromasia and irregular nuclear contours remain the most reliable cellular characteristics for diagnosing SIL in atrophic CVS. [See editorial on pages 200-1, this issue.] Cancer (Cancer Cytopathol) 1998;84:218-225. © 1998 American Cancer Society.