Encapsulated papillary carcinoma of breast; a clinicopathological study of 25 cases and literature review with emphasis on high grade variant.

Encapsulated Papillary Carcinoma (EPC) is a rare breast tumor with excellent prognosis. Treatment and stage of EPC is influenced by invasion and high nuclear grade. Our aim was to study the clinicopathological features of EPC, especially high grade tumors and to compare the features of invasive and non-invasive tumors. We reviewed clinicopathological features of 25 cases of EPC diagnosed at our institution from 2006 till 2020. Patients' age ranged from 21 to 75 years (median 55 years). Tumor size ranged from 1 to 9 cm (median 3.5 cm). Overall, invasion was present in 44% cases. High nuclear grade was observed in 24% cases. Majority of these high grade tumors were below 40 years. All of these tumors were 4 cm or larger in size. Two third of these tumors were invasive. Hormone receptor negativity and lymph node involvement was observed in 1 out of 3 cases, when performed. Clinicopathological and histological features of invasive and non-invasive tumors were compared and only lymph node involvement was found to be significantly more frequent in invasive tumors (p = 0.049). Median follow up duration was 18 months. All patients were alive and disease free except for a single patient who died of cerebrovascular accident. EPC has excellent clinical course. Invasion and high nuclear grade should be carefully searched for as these features determine tumor stage and treatment.