Expansively Hemorrhagic Foreign Body Granuloma at the Pelvis Caused by Microscopic Materials

A foreign body granuloma is a mass lesion consisting of a foreign body with host reaction. Its diagnosis is not always easy in respect of its similarity to soft tissue sarcoma. The most common foreign body is surgical sponge which can be detectable macroscopically. We present a foreign body granuloma in the left buttock caused by microscopic surgical materials that developed into a large lesion. An 80-year-old man with a history of surgery for dislocation of the left hip 20 years earlier, presented with a slowly growing mass that had expanded rapidly over the preceding 2 months. Histological examination revealed organizing granulation tissue surrounding the scattered foreign materials. One should be aware of foreign body granuloma at previously operated sites even without a retained macroscopic gauze sponge.