Metastasis from follicular lymphoma to an ovarian mature teratoma: a case report of tumor-to-tumor metastasis

BackgroundTumor-to-tumor metastasis (TTM) is a rare but well-established phenomenon where histologically distinct tumors metastasize within each other. Here we report the first "known" case of follicular lymphoma that metastasized and extended to a mature ovarian teratoma.CasepresentationA59-year-old Japanese postmenopausal woman visited our hospital for a detailedexamination of an ovarian tumor. Clinical imaging suggested it to be eitherteratoma-associated ovarian cancer with multiple lymph node metastases, ortumor-to-tumor metastasis from malignant lymphoma to ovarian teratoma. Abilateral adnexectomy and retroperitoneal lymph node biopsy were performed.Lined with squamous epithelium, the cyst constituted a mature ovarian teratoma,and the solid part showed diffuse proliferation of abnormal lymphoid cells.Immunohistochemically, the abnormallymphoid cells were negative for CD5, MUM1, and CyclinD1, and positivefor CD10, CD20, CD21, BCL2, and BCL6. Genetic analysis using G-banding andfluorescence in situ hybridization identified a translocation of t(14;18)(q32;q21), and we diagnosed tumor-to-tumor metastasis from nodal follicular lymphomato mature ovarian teratoma. Twelve months after surgery, the patient showed noprogression without adjuvant therapy.ConclusionsThe present case suggests thatmolecular approaches are useful in the diagnosis of TTM in mature ovarianteratomas when morphologic and immunohistochemical findings alone are insufficientfor diagnoses.