Metastatic carcinoma of the prostate mimicking primary carcinoid tumor of the lung and mediastinum

Fine needle aspiration of thymic epithelial neoplasms and non-neoplastic lesions

Thymic epithelial neoplasms are rare as these tumors represent less than 1% of all human tumors. In addition, thymic hyperplasia and thymic cysts can also present as anterior or less often superior mediastinal masses. Fine needle aspirates and core biopsies of thymic epithelial neoplasms are rarely encountered in routine pathology practices. Histologic classification of these lesions requires microscopic examination of the entire lesion as a significant number of tumors can have more than one histologic type and the status of invasion into adjacent soft tissues or organs is needed for accurate staging. Therefore, it is important to understand the limitations of the information these biopsy methods can provide. The accuracy of the diagnosis can be improved by using ancillary techniques like immunohistochemistry and flow cytometry. In this review, we are summarizing the clinical, histologic and cytologic characteristics of thymic cysts, thymic hyperplasia and thymic epithelial neoplasms including different types of thymoma and thymic carcinoma.

Secondary prostatic adenocarcinoma: A cytopathological study of 50 cases

Positive diagnosis of metastatic prostate adenocarcinoma (PAC) can be made by microscopic examination of the cytologic specimens and immunostaining for prostate-specific antigen (PSA) and prostate acid phosphatase (PAP). Immunohistochemical markers have been known to display negative, weak, or focal staining in poorly differentiated PAC and in patients with prior hormonal and/or radiation therapy. The purpose of this study is to characterize the cytopathology of metastatic PAC as it has not been documented in large series. Fifty cases of metastatic PAC with cytological specimens consisting of 41 fine-needle aspiration biopsies (FNAB), 6 pleural fluid aspirates, and 3 catheterized urine samples were reviewed and correlated with the surgical specimens and the clinical charts. Immunostaining for PSA, PAP, cytokeratin AE1/3, cytokeratin 7 (CK7), cytokeratin 20 (CK20), vimentin, and carcinoembryonic antigen (CEA) was done. Mean patient age was 77 +/- 8 yr; serum PSA, 4.1 +/- 2.3; and primary PAC Gleason score, 8.1 +/- 1.5. Cytologically, the specimens consisted of cell clusters or cell sheets with overlapping uniform hyperchromatic nuclei with or without nucleoli. Twelve cases were not reactive to PSA and PAP and 44 cases displayed negative immunoreactivity to both CK7 and CK20. Carcinoid-like lesions and small cell carcinomas were seen in 4 cases and were misdiagnosed as nonprostatic origin based on the following features: negative immunoreactivity to PSA and PAP with or without positive reactivity to CEA, and different histopathological features when compared with the primary PAC. In addition to the frequency of high-grade PAC, awareness of the negative immunoreactivity to PSA and PAP, the discrepancy in the histopathological patterns between the primary and secondary tumors, especially the frequent neuroendocrine differentiation, are helpful features for the diagnosis of metastases of prostatic origin.

The morphologic spectrum of metastatic prostatic adenocarcinoma to the lung: special emphasis on histologic features overlapping with other pulmonary neoplasms

We undertook a detailed histologic study to identify specific morphologic features that may aid in distinguishing prostatic adenocarcinoma with lung metastases (PALM) from other pulmonary tumors with similar histologic features. In 16 cases, we found 3 predominant architectural patterns: microacinar (n = 10), tubulopapillary (ductal; n = 4), and carcinoid-like (n = 2). Characteristic features of PALM included small acinar and/or cribriform growth, frequent lymphangitic permeation, lack of stromal response, uniform round nuclei with prominent nucleoli, intraluminal blue mucin, and prominent cell borders. By immunohistochemical staining, prostate-specific antigen and prostate-specific acid phosphatase were present in 13 of 14 and 13 of 13 cases, respectively. Metastatic prostatic duct adenocarcinoma exhibited morphologic features similar to metastatic colonic adenocarcinoma. Two cases had a carcinoid-like appearance with nested or solid architecture, parachromatin clearing, and prominent nucleoli, but lacked the finely stippled chromatin pattern of carcinoid tumors. Several features that may result in misinterpretation or lack of association of the neoplasm in the lung with a prostatic primary include lung metastasis preceding the detection of a prostatic primary tumor, solitary pulmonary nodule, tubulopapillary (ductal) or carcinoid-like pattern, scant material in which histologic features of metastatic prostate carcinoma are not fully appreciated, and frequent necrosis. Attention to specific discriminating histologic features, supported by immunohistochemical staining, may be useful in the differential diagnosis, which is therapeutically and prognostically critical.