Displaced granulosa cells in the fallopian tube mimicking small cell carcinoma.

A case is reported where displaced non-neoplastic ovarian granulosa cells within the fallopian tube mimicked a small cell carcinoma. This peculiar phenomenon of displaced granulosa cells has been described previously in the ovary as a rare diagnostic pitfall which may be misinterpreted as metastatic carcinoma. This is believed to be the first documentation of its occurrence in the fallopian tube. Awareness of this rare phenomenon and immunostaining for markers of sex cord differentiation assist in diagnosis and in preventing a false positive diagnosis of malignancy.