Application of the Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) for the Evaluation of Clinical Behavior of Carotid Body Paragangliomas
KT Montone, J Seol, LA Loevner, ZW Baloch, VA Livolsi. University of Pennsylvania, Phila, PA
Background: Carotid body paragangliomas share histologic features with pheochromocytomas. Few studies have detailed the pathology associated with aggressive behavior. In 2002, Thompson (Am J Surg Pathol. 2002;26(5):551) developed the Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) to assess which histologic parameters could predict which tumors may act in an aggressive fashion. Tumors with a PASS <4 were benign. We adapted this scoring system for evaluating carotid body tumors.
Design: 39 carotid body tumors were studied. Tumors were evaluated using PASS with scoring as follows: capsular invasion (1 point), vascular invasion (1 point); adipose tissue invasion (1 point), large nests/diffuse growth (2 points), high cellularity (2 points), cellular spindling (2 points), monotony (2 points), mitoses (>3/10 high power fields; 2 points), atypical mitoses (2 points), profound nuclear pleomorphism (1 point), and hyperchromasia (1 point). Necrosis was excluded from the PASS since almost all of the carotid body tumors had been embolized prior to resection.
Results: All 39 cases were confirmed paragangliomas. 3 were malignant because of metastases to lymph nodes (2) and lung (1). An additional 4 patients had multiple tumors either involving the opposite carotid body or the middle ear. PASS ranged from 2-12 with an average of 4.8. The most common histologic feature was profound nuclear pleomorphism (30 patients) followed by capsular invasion (14 patients), spindle cell change (13 patients), vascular invasion (12 patients) and cellular monotony (12 patients). The least common features were high mitotic activity (4 patients 2 of which were malignant) and atypical mitoses (2 patients both malignant). 37 patients are alive with no evidence of disease and 2 patients are alive with disease. No patient has died of disease. 21 patients had PASS > or = 4. The three malignant paragangliomas had PASS >4 (5, 8, and 12). The 18 remaining patients with PASS >4 have shown no recurrence. The patients with PASS <4 are alive with no evidence of disease.
Conclusions: While most patients with PASS >4 behave in a non-aggressive fashion, PASS can identify patients with carotid body tumors at risk for aggressive behavior. All malignant paragangliomas had scores >5. Mitoses and atypical mitoses are rare in carotid body tumors and their presence may indicate aggressive behavior. The presence of metastases is compatible with prolonged survival in carotid body paragangliomas.
Category: Head & Neck
Tuesday, March 10, 2009 2:00 PM
Platform Session: Section H, Tuesday Afternoon