PEComa (clear cell "sugar" tumor) of the lung is a rare benign tumor of the lung probably arising from the perivascular epithelioid cells (PECs). We report a case of pulmonary PEComa arising from the periphery of the right lobe of a 64-year-old male. To our knowledge, this is the second case in the English literature diagnosed by fine needle aspiration biopsy. In this case report, the clinical, cytologic and immunohistochemical features clear cell "sugar" tumor of the lung are discussed and compared with the previously published literature. The differential diagnosis and methods for distinguishing the various clear cells lesions in the lung are discussed.

The Pap test (PT) is most commonly used as a screening test; however, it is often also used as a "diagnostic test," usually in patients of known or suspected lesions. As we have recently shown that the yield of atypical interpretations in diagnostic Pap tests (DPTs) is nearly five times greater than the yield for screening Pap tests (SPTs), we speculated that the PT might function differently when used in each population. The University of Virginia's cytologic-histologic correlation results for PTs, accessioned between 4 January 2003 and 11 December 2003, were reviewed. PTs were considered as SPTs or DPTs, depending on the billing codes used by referring physicians. Using the original diagnosis, results were compared for SPTs and DPTs using chi-square testing. There were 1,311 PTs (776 DPTs and 535 SPTs), which had histologic follow-up within a 7-mo period. Of SPTs interpreted as negative (242), 11 (4.5%) showed SIL or worse and 3 (1.2%) showed HSIL or worse on follow-up biopsy. Of SPTs interpreted as ASC (133), 59 (44.3%) showed SIL or worse and 16 (12.0%) showed HSIL or worse on follow-up biopsy. Of SPTs interpreted as LSIL (117), 65 (55.5%) showed SIL or worse and 17 (14.5%) showed HSIL or worse on follow-up biopsy. Of SPTs interpreted as HSIL (38), 31 (81.6%) showed SIL or worse and 23 (60.5%) showed HSIL or worse on follow-up biopsy. Of SPTs interpreted as glandular lesions (AGC, adenocarcinoma, etc.) (4), 3 (75%) showed HSIL or malignancy. Of DPTs interpreted as negative (261), 69 (26.4%) showed SIL or worse and 10 (3.8%) showed HSIL or worse on follow-up biopsy. Of DPTs interpreted as ASC (166), 75 (45.2%) showed SIL or worse and 22 (13.3%) showed HSIL or worse on follow-up biopsy. Of DPTs interpreted as LSIL (227), 146 (64.4%) showed SIL or worse and 31 (13.7%) showed HSIL or worse on follow-up biopsy. Of DPTs interpreted as HSIL (119), 105 (87.4%) showed SIL or worse and 84 (70.6%) showed HSIL or worse on follow-up biopsy. Of DPTs interpreted as glandular lesions (AGC, adenocarcinoma, etc.) (3), 3 (100%) showed HSIL or malignancy. Overall, DPTs were more likely than SPTs to show SIL or HSIL on follow-up biopsy (P < 0.01), and negative DPTs were more likely than negative SPTs to show SIL or HSIL on follow-up biopsy (P < 0.01, P = 0.01, respectively). Some of this may be a reflection of the increased percentage of LSIL and HSIL results for DPTs. Despite the difference in disease prevalence between women having SPTs and those having DPTs, the PT seems to function relatively the same in both scenarios, except in high risk women with negative DPTs.