Unusual Calcifying Fibrous Tumor in the Fallopian Tube: Review and Discussion of the Differential Diagnosis

Calcifying fibrous tumor (CFT) is a rare benign soft tissue tumor of unknown etiology and extremely rare in female reproductive system. We present a case of unusual CFT in the ampulla of fallopian tube occurring in a middle-aged female patient with multiple uterine leiomyomas. A hysterectomy was performed on a 48-year-old woman for uterine leiomyomas. At surgery, a solitary, well-defined nodule, measuring 1.0 cm in diameter, was incidentally observed on the wall of ampulla of right fallopian tube. The lesion of fallopian tube was resected totally. Histologically, this lesion was unencapsulated and composed of hyalinized collagenous fibrous tissue with psammomatous calcification and focal lymphoplasmacytic infiltrate. Sparsely fibroblast-like spindle cells were scattered in the dense hyalinized background with bland nuclei. By immunohistochemistry, vimentin was diffusely positive in most cells, and a focal reactivity for CD34 was also observed in spindle cells. However, they were negative for cytokeratin (AE1/AE3), S-100 protein, CD117, DOG1, SMA, desmin, and ALK. The Ki-67 labeling index of the lesion was <1%. A diagnosis of primary CFT of fallopian tube was made. To our knowledge, this is the first report of CFT occurring in female reproductive tract. Awareness of CFT and its distinctive features is important to avoid a diagnostic pitfall caused by histologic similarities to other spindle cell or calcifying lesions in unusual locations. Although marginal excision is usually adequate for most of CFT, long-term follow-up is suggested as delayed recurrence might occur infrequently.