title: Soft tissue metastasis of thyroid carcinoma in the knee region mimicking a paraarticular inflammatory lesion.
abstract: We report a case of a 57-year-old male patient presenting with a painful mass in the popliteal fossa of the left knee, while the X-ray being unremarkable, MRI suggested a paraarticular lesion such as an inflamed paraarticular ganglion. A biopsy showed a poorly differentiated metastasis of a papillary thyroid carcinoma, the patient had been operated on 8 years ago. This case emphasizes that in patients with malignancies such as papillary thyroid carcinomas long-term courses (over years) with several phases of tumor spread occur finally leading to filiae in any location. Thus, in such patients, a metastatic lesion even in unusual places such as the periarticular soft tissue should be included in the differential diagnosis.
authors.affiliation: Orthopedic Hospital, University of Leipzig, Leipzig, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Prietzel
authors.forename: Anna
authors.initials: A
authors.lastname: Macher
authors.forename: Irina
authors.initials: I
authors.lastname: Haferkorn
authors.forename: Nicole
authors.initials: N
authors.lastname: Schmitz
authors.forename: Frank
authors.initials: F
authors.lastname: Schmidt
authors.forename: Thomas
authors.initials: T
authors.lastname: Aigner
mesh_terms: D002291:Carcinoma, Papillary / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D007249:Inflammation / Q000175:diagnosis; D007717:Knee; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary*; D013964:Thyroid Neoplasms / Q000473:pathology*