Multiple plaques on the back: S-100 negative benign granular cell tumor.

Granular cell tumor is a rarely seen disease characterized by a gradually developing nodular lesion, which is difficult to diagnose. It has been thought to originate from Schwann cells. The tumor usually appears in the 4th-6th decades of life, more frequently in women and blacks, and has a multifocal location in 10-25% of the cases. The malignancy potential is 1-3%, with 70-74% of the cases in women. Ninety-eight percent of the cases are S-100 positive. The present paper describes an 18-year-old female patient with benign granular cell tumor. This rarely seen type of tumor was S-100 negative and has been detected in biopsies taken from multiple asymptomatic plaques and maculopapular lesions. They were 0.5-4 cm in diameter, light brown in color, and with clear contours and had been gradually growing on her back the last nine years.