We investigated the morphological features of Trichomonas vaginalis in liquid-based Papanicolaou (Pap) (LBP) tests, in order to assess the impact of this new slide preparation system on recognition of T. vaginalis organisms. We reviewed 88 LBP test slides previously interpreted as showing T. vaginalis and assessed morphological characteristics of the organisms and the presence of secondary features. Eighty-six of 88 slides showed, at least focally, organisms with cytoplasmic granules, nuclei, and flagella allowing for confident recognition of T. vaginalis. Compared with 58 controls, cases of T. vaginalis were more likely to have squamous cells with perinuclear halos, "ghost cells," and coccobacilli. The lack of a "dirty" background or cytolysis allowed a more straightforward identification of the organisms. We concluded that T. vaginalis organisms are morphologically distinct in LBP tests, which may lead to an increased specificity when they are identified in such tests.
Thymic carcinoid tumors (well-differentiated neuroendocrine carcinomas) are uncommon anterior mediastinal neoplasms. These tumors are frequently accompanied by other endocrinopathies as part of a multiple endocrine neoplasia type I syndrome (MEN type I) and by paraneoplastic Cushing's syndrome and have a poor prognosis. We present the case of a 24-year-old man who presented for follow-up of thymic carcinoid with extensive bony metastases. He had recently completed radiotherapy to lesions involving his skull and mandible. An ultrasound-guided left-sided diagnostic and therapeutic thoracentesis was performed yielding 1 l of cloudy yellow fluid. The cytologic fluid preparations consisted of large "cannonballs" and atypical cell groups with salt and pepper nuclear chromatin. A panel of immunohistochemical stains were performed on the cell block material, and the atypical cells were positive for cytokeratin, synaptophysin, and chromogranin, but not for TTF1. These findings were consistent with metastatic well-differentiated neuroendocrine carcinoma (carcinoid tumor). This is the first reported case of a carcinoid tumor manifesting as large, spherical, smoothly contoured cell aggregates ("cannonballs") in a pleural fluid. Despite its rarity, a metastatic carcinoid tumor should be considered when "cannonballs" are found in effusions.
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