Critical clinical appraisal of the role of computed tomography-guided minimally invasive aspiration cytology in evaluation of retroperitoneal masses

Minimally invasive biopsy in retroperitoneal tumors

Minimally invasive biopsy procedures have proven over the years to be essential for obtaining a correct diagnosis of retroperitoneal tumors, that allows proper therapeutical conduct. These procedures offer valuable tissue fragments for histopathological examination, that permits the distinction between benign and malignant tumors, identifying the tumors that can benefit from neo-adjuvant treatments, such as chemotherapy or radiotherapy and those that have a direct surgical indication. We have searched the existing data regarding minimally invasive biopsy in retroperitoneal tumors using the PubMed database, in order to evaluate the role of this procedure in establishing a correct diagnosis, as well as to find out the risks of tumor cell seeding and local recurrence after needle biopsy. The risk of tumor cell seeding is very low (<2%) and in some cases, it is considered negligible (<0.5%). Compared to open biopsy, needle biopsy seems to be associated with a significantly lower risk of tumor cell seeding. According to the existing data, the incidence of needle track tumor cell seeding also depends on the histological type of the tumors. Image-guided retroperitoneal biopsy has proven to be low cost, accessible, and a reliable procedure (in terms of diagnostic accuracy), usually associating with a low rate of complications and a low risk of tumor seeding. Several authors have underlined the importance of the retroperitoneal approach and the association with a co-axial imaging technique in order to avoid potentially deadly complications.

Fine needle aspiration in retroperitoneal lesions

The retroperitoneal space is a potential space extending from lumbar to the pelvic region, behind the peritoneum. It encloses many vital organs like adrenals, kidneys, ureters, pancreas, aorta and its branches, inferior vena cava and its tributaries and many lymph nodes along with loose connective tissue and fat. The literature regarding role of fine needle aspiration cytology (FNAC) for diagnosis of retroperitoneal lesions as a whole, is exceedingly limited. The present study was conducted to elucidate the spectrum of retroperitoneal lesions and to determine the diagnostic accuracy of fine needle aspiration cytology, presenting to a tertiary care referral centre. A total of 389 aspirates from retroperitoneal lesions were reviewed for clinical and radiological details. The smears were studied for the cytological diagnosis. Cytological-histological correlation was assessed and the causes for discordant diagnoses were determined. The patients' age ranged from 1 to 88 years. There were 234 (60.2%) males and 155 (39.8%) females. In 61 (15.7%) aspirations, the yield was inadequate for reporting and 328 were satisfactory. About 113 (29.0%) aspirates were from pancreatic masses alone, 97 (24.9%) from the retroperitoneal lymph nodes, 70 (17.9%) from the kidneys, 45 (11.5%) from the adrenals, 41 (10.5%) from the retroperitoneal soft tissues and 23 (5.9%) from retroperitoneal segments of the gut. There were 249 (64.0%) neoplastic lesions and 79 (20.3%) non-neoplastic lesions, the ratio being 3.1:1. Eight (2.0%) aspirates were reported as suspicious for malignancy, and 5 (1.2%) aspirates were reported as neoplastic but could not be categorized as benign or malignant. Of the neoplastic lesions, malignant neoplasms (n = 216; 87.1%) were much more common than the benign (n = 20; 8.0%), the ratio being 10.8:1. Of all the satisfactory aspirates, subsequent histopathology was available only in 33/327 (10%) cases. A positive correlation between cytological and histological diagnosis was observed in 27/33 (81.8%) cases. We believe FNAC is a useful method for an early, rapid, minimally invasive and reliable pre-operative diagnosis for retroperitoneal lesions and can often obviate the need for open surgical biopsy.