RT Book, Section A1 Barrio, Victoria R. A1 Eichenfield, Lawrence F. A2 Rudolph, Colin D. A2 Rudolph, Abraham M. A2 Lister, George E. A2 First, Lewis R. A2 Gershon, Anne A. SR Print(0) ID 7033284 T1 Chapter 363. Neoplastic and Proliferative Disorders T2 Rudolph's Pediatrics, 22e YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-149723-7 LK accesspediatrics.mhmedical.com/content.aspx?aid=7033284 RD 2024/03/28 AB Dermatofibromas (fibrous histiocytomas) are red-to-brown, firm nodules, ranging in diameter from a few millimeters to 2 centimeters. These benign lesions are often located on the lower extremities and tend to persist indefinitely. Lateral pressure on the lesion produces dimpling of its surface.1 Larger lesions may be concerning for dermatofibrosarcomaprotuberans, which is a rare, more invasive lesion. Biopsy is diagnostic in both cases and may be necessary to distinguish the lesions. Biopsy of a dermatofibroma reveals prominent fibrocytes and coarse bundles of collagen in a haphazard fashion, frequently arranged in short fascicles that interweave (“storiform pattern”). There is often hyperplasia and hyperpigmentation of the overlying epidermis.2Dermatofibrosarcoma protuberans is usually located on the trunk, often has a blue hue, and may be mistaken for a vascular lesion.3 It is locally invasive and may only rarely metastasize. Wide local excision or Mohs surgery is indicated, and preoperative MRI may help delineate the extent of the lesion before surgery.4