MRI "row of dots sign" in gossypiboma: an enlarging mass 8 months after sarcoma resection.

The retention of foreign bodies after surgery is rare, but carries significant morbidity and mortality as well as financial and legal implications. Such retained items cause a foreign-body reaction, which in the case of cotton-based materials are called gossypibomas. We present the case of an 84-year-old woman with a pseudotumor secondary to a retained dressing gauze roll, presenting 5 months after resection of a gluteal sarcoma, which had raised concerns of local recurrence. We also outline the imaging modalities that may assist in diagnosis of a retained foreign body, and suggest the MRI "row of dots" sign as a useful radiological feature associated with gossypiboma. Awareness of the imaging appearances of retained foreign bodies allows the inclusion of this possibility in differential diagnosis of a mass in patients with a surgical history.