Abstract
A 50-year-old man suffering from neurofibromatosis type 1 noticed a subcutaneous tumor (30×30 mm) on his right lower back in 1999. We carefully observed this tumor and identified it as a neurofibroma. But he had not come to our hospital since 2009. The tumor grew gradually and caused redness and swelling in June 2012. When he came to our hospital in July 2012, the size of the tumor was 20×16 cm. MRI of the tumor revealed a polycystic subcutaneous tumor, approximately 12×12 cm, on his right lower back. We diagnosed intratumoral bleeding of malignant peripheral nerve sheath tumor (MPNST) because his tumor enlarged rapidly and his anemia worsened. An immediate excision of the tumor was performed after embolization therapy. The tumor was histologically diagnosed as an MPNST. As the surgical margin was pathologically negative without distant metastasis, no chemotherapy or radiotherapy were performed after the surgical treatment. He has been free from recurrence or metastasis for at least nine months.[Skin Cancer (Japan) 2013 ; 28 : 306-309]
