Objective: To elucidate the clinicopathologic characteristics of atypical epithelioid trophoblastic lesions with cyst and fistula formation after cesarean section. Methods: The clinical and pathological data of 4 cases of post-cesarean atypical epithelioid trophoblastic lesions with cyst and fistula formation diagnosed at Women′s Hospital, School of Medicine, Zhejiang University during April 2007 to June 2018 were evaluated by hematoxylin and eosin stain and EnVision two-step immunohistochemical staining technique. Results: The age of the 4 patients ranged from 32 to 41 years, with a mean age of 36.5 years. Three patients recieved cystectomy and one underwent subtotal hysterectomy. Histologically, the lesions were well circumscribed and consisted of uniform cells of medium size, irregularly enlarged with hyperchromatic nuclei and 1 to 2 inconspicuous nucleoli embedded in abundant hyalinized matrix with fibrinoid material in the center. The cells exhibited immunohistochemical feature of chorionic-type intermediate trophoblastic cells (CK18+, p63+ and CD146-). All patients were alive without recurrence during follow-up of 1 to 40 months (mean=22 months). Conclusion Atypical epithelioid trophoblastic lesion with cyst and fistula formation after cesarean section has unique histological features, and its biological behavior and prognosis are still unclear, which need further exploration.