Fine needle aspiration and core needle biopsy of metastatic malignancy of unknown primary site

Abstract

Metastatic malignancies of unknown primary site (MUP) is the eighth most common form of malignancy, with an estimated 10-15% of oncology patients having a MUP. Fine needle aspiration cytology (FNA) and core needle biopsy (CNB) are often the first procedures utilized in the work-up of these cases and have a pivotal role for the diagnosis of metastases. There is an increasing emphasis on the precise classification of malignancy and determination of primary site of origin, utilizing smaller specimens. Recent available data suggest that there is a management benefit in identifying the primary site and/or specific cell lineage of MUP. In addition, the pathologists are asked to preserve the limited diagnostic material for potential molecular testing, as selected patients may benefit from targeted therapy. However, these tasks can become extremely challenging, especially if there is no previous history of malignancy, prior pathology is not available for review, or there is an unpredictable pattern of metastasis. In this review, we present a contemporary clinicopathologic approach to the workup of MUP that includes cytomorphology, ancillary studies, and clinicopathologic correlation. The cytohistologic subclassification of malignancies into specific cell lineages and/or morphologic categories is presented. Knowledge of the various patterns of metastasis to common and unusual sites can help narrow down the location of a primary site. The use of ancillary studies with particular emphasis on IHC utilizing an algorithmic approach and the role of molecular analysis as a diagnostic and theranotic test are also discussed. When the cell block and/or CNB lacks sufficient material for ancillary testing, the cell transfer technique may be utilized.

Core Needle Biopsy Can Early and Precisely Identify Large Thyroid Masses

“…Conversely, when the histology is known, as in most cases of CNB, a specific molecular profile can be studied, being different not only according to different tumors ( 43 ) but also in the context of different thyroid tumors ( 44 , 45 ). Accordingly, in metastatic malignancies for which the primary site is unknown, the key role of CNB compared to FNAC has been clearly demonstrated, both in clarifying the primary site of the tumor and in obtaining sufficient material to perform the molecular analysis ( 8 , 46 ).…”

Diagnostic clues for differentiating Merkel cell carcinoma from lymphoma in fine‐needle aspiration cytology

“…22 Lymphoglandular bodies are valuable in alerting the (cyto) pathologists to the possibility of NHL. 5,19 We demonstrate that presence of nuclear molding, Indian filing, and absence of lymphoglandular bodies are the diagnostic features of MCC. 19 In cases suspicious for lymphoma, ancillary studies such as immunocytochemistry, flow cytometric immunophenotyping, and clonality assay may help differentiating lymphoma from MCC.…”

“…Fine-needle aspiration cytology (FNA) of small round cell tumors can be diagnostically challenging. 5,6 In the literature, most published studies of the cytologic findings of MCC are single case reports or small series. [7][8][9][10][11][12][13][14][15][16] As the cytomorphology of MCC may mimic other malignancies, particularly lymphoma and pulmonary small cell carcinoma (SmCC), 7,9,10,[12][13][14] immunocytochemistry is useful in confirming the diagnosis.…”

Transvaginal Ultrasound-Guided Core Biopsy—Experiences in a Comprehensive Cancer Centre

“…Due to the heterogeneity of many gynaecological tumours, we believe a core biopsy might be advantageous over a fine needle aspiration biopsy because it provides more detailed information about tissue structure. Diagnostic and prognostic immunohistochemical and molecular examinations can be performed from the sample; moreover, they can guide therapeutic decisions [ 21 , 26 , 27 , 28 ]. Still, tumour heterogeneity resulted in inaccurate histological diagnosis in 6 of the 94 analysed patients.…”