Cytologic analyses of spindle‐cell lesions of the thorax and retroperitoneum

Abstract

Thoracic and retroperitoneal spindle-cell lesions represent a diagnostic challenge in the evaluation of fine-needle aspiration (FNA) specimens. The challenge is due to the morphologic similarities and wide variety of different entities with spindle-cell morphology in these two sites. The purpose of this study was to identify criteria helpful in the classification and differential diagnosis of spindle-cell lesions in these two locations. A set of cytologic features was analyzed in 57 thoracic or retroperitoneal spindle-cell lesions. Our results show that pleomorphism and abundant single cells were parameters associated with high-grade tumors in univariate and multivariate analysis, while coarse chromatin pattern was significant only in a univariate analysis. The combination of absence of pleomorphism, rare single cells, tight cluster arrangement, fine chromatin pattern, and absence of macronucleoli was seen only in benign cases. Assessment of background material was helpful in the differential diagnosis and classification. Necrosis was only found in high-grade cases.

Transthoracic Fine-Needle Aspiration Cytology of Pulmonary Spindle and Mesenchymal Neoplasms: A Pandora’s Box

“…Dispersed single cells, mitosis, necrosis, macronucleoli, or pleomorphism was not observed in any of these benign cases. Concordant findings have been reported by Lin et al [6]. Thus, combination of these features along with imaging helps exclude malignancy and consequently eliminate the need for neoadjuvant chemotherapy.…”

“…Thoracic FNA has reported high specificity ranging from 78 to 90% with a sensitivity ranging from 85.7 to 92%. The high sensitivity and specificity are due to the predominance of epithelial and lymphoid tumours at this site, and their diagnosis as malignant usually does not represent a problem; however, mesenchymal lesions are considerably more difficult to classify [6]. Previous studies in the literature have shown that diagnostic accuracy of FNA is 63-95% for mesenchymal lesions [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

“…The high sensitivity and specificity are due to the predominance of epithelial and lymphoid tumours at this site, and their diagnosis as malignant usually does not represent a problem; however, mesenchymal lesions are considerably more difficult to classify [6]. Previous studies in the literature have shown that diagnostic accuracy of FNA is 63-95% for mesenchymal lesions [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In our cohort, high diagnostic accuracy of 93.8% was observed in differentiating benign neoplasm from malignancies on cytomorphology.…”

Cytomorphologic features that distinguish schwannoma from other low‐grade spindle cell lesions

“…It is interesting to note that benign mesenchymal spindle cell lesions have been reported to lack single cells. 17,31 We identified occasional epithelioid cells in 3 schwannomas, and a case of an exclusively epithelioid schwannoma has been reported previously. 32 Thus, the presence of epithelioid cells does not exclude the possibility of an otherwise benign-appearing spindle cell lesion being diagnosed as a schwannoma.…”

“…Similarly, single cells with bipolar cytoplasmic processes were observed in a significant number of low‐grade but aggressive lesions that could be confused with schwannomas, including low‐grade fibromyxoid sarcoma (66%), fibromatosis (80%), GIST (70.6%), and solitary fibrous tumor (75%). It is interesting to note that benign mesenchymal spindle cell lesions have been reported to lack single cells …”