Cytology and Pitfalls of EUS Sampling of Ectopic Splenic Tissue
Joseph Mitros, Ryan Askeland, Chris Jensen. University of Iowa, Iowa City, IA
Background: Ectopic splenic tissue is common and can occur in a variety of sites but most frequently the splenic hilum. Although often noted as incidental masses on imaging studies including endoscopic ultrasound (EUS), ectopic splenic tissue may not be recognized if outside the usual splenic hilum due to variable EUS characteristics. EUS-guided fine needle aspiration (EUS-FNA) is used to evaluate abdominothoracic masses and ectopic spleen may occasionally be sampled. Cytologic recognition of ectopic spleen at the time of EUS may be difficult due to the relative rarity of splenic aspirations in most practice settings as well as the varied clinical features. Knowledge of the clinical, EUS, and cytologic features of ectopic splenic tissue is important for the cytologist interpreting EUS-FNA's.
Design: A retrospective search of the laboratory information system (LIS) identified 35 aspirations of spleen over 10 years including 10 EUS FNA cases with ectopic splenic tissue. The 10 cases included 6 males and 4 females with a mean age of 47.7 years. Two cases had corresponding surgical pathology material.
Results: Ectopic splenic tissue sampled by EUS FNA was located within the pancreas (4), peripancreatic (3), intrahepatic (2), and within the gastric wall (1). Size ranged from 0.5 to 3.5 cm (mean 1.77 cm) with a variety of EUS echo intensities ranging from hypoechoic to hyperechoic. Intraprocedural preliminary cytologic diagnoses were varied with two cases suspicious for neoplasm. The majority (8) were noted to be lymphoid tissue with no cases interpreted as splenic tissue onsite. The smears were variably cellular with a mix of small lymphocytes and tissue fragments. Tissue fragments commonly showed crush artifact and were composed of a mix of spindle cells and lymphocytes. Immunohistochemistry was performed in two cases with coexpression of CD8 and vascular markers CD31 or CD34.
Conclusions: 1. EUS FNA sampling of ectopic spleen is often located away from the splenic hilum and may be do to less frequent recognition by EUS, atypical EUS features, and/or overlapping imaging characteristics with other lesions such as lymph nodes and pancreatic neuroendocrine tumors.
2. Two cases were given preliminary diagnoses of suspicious for neoplasm which highlights the potential pitfall in the cytologic interpretation of ectopic splenic tissue.
3. Accurate diagnosis is facilitated by awareness of the varied locations of ectopic splenic tissue, knowledge of the cytologic appearance of the spleen, and communication with the endoscopist.
4. In some cases, immunohistochemistry may be a useful adjunct in confirming the cytologic diagnosis.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 59, Tuesday Morning