© 2009 The International Society of Dermatology International Journal of Dermatology 2009, 48, 275–279 275 Abstract Plexiform neurofibroma in neurofibromatosis type 1, an autosomal-dominant genetic disorder, is characterized by a combination of interlacing components or a network. The prominent enlargement of a nerve with tumor nodules results in the gross pathologic appearance termed “bag of worms.” Plexiform neurofibroma was found in two of seven family members with neurofibromatosis type 1 in three generations. Ultrasonography/color doppler and magnetic resonance imaging, in addition to microscopic pathology, were used as diagnostic tools, and their indications for future use in the diagnosis of plexiform neurofibroma are highlighted. Blackwell Publishing Ltd Oxford, UK IJD International Journal of Dermatology 0011-9059 1365-4632 Blackwell Publishing Ltd, 2008 XXX Medical genetics Evaluation of plexiform neurofibroma in NF1 Sehgal, Sharma, and Oberai Medical genetics Evaluation of plexiform neurofibroma in neurofibromatosis type 1 in 18 family members of 3 generations: ultrasonography and magnetic resonance imaging a diagnostic supplement Virendra N. Sehgal, MD, FNASc, FAMS, FRAS(Lond.), Sonal Sharma, MD, and Rakesh Oberai, MD From the Dermato-Venereology (Skin/VD) Centre, Sehgal Nursing Home, Panchwati, Delhi, University College of Medical Sciences and Associated GTB Hospital, Delhi, and Ganash Diagnostic and Imaging Centre, Rohini, New Delhi, India Correspondence Virendra N. Sehgal, MD, FNASc, FAMS, FRAS(Lond.) Sehgal Nursing Home Dermato-Venereology (Skin/VD) Centre A-6 Panchwati Delhi 110 033 India E-mail: drsehgal@ndf.vsnl.net.in Introduction The term neurofibromatosis (NF) encompasses a set of autosomal-dominant genetic disorders characterized by neurofibromas, café-au-lait spots, intertriginous freckling, Lisch nodules, optic gliomas, and bony dysplasia. Neuro- fibromatosis type 1 (NF1) affects only two to three individuals per 10,000 population. 1 Plexiform neurofibroma (PN) is commonly seen in patients with NF1, and is usually first noted in children with NF1 approaching adolescence. PN exhibits diffuse involvement along a nerve and its branches, and is characterized by a combination of interlacing com- ponents or a network. The prominent enlargement of a nerve with tumor nodules results in the gross pathologic appearance termed “bag of worms.” PN can extend superficially beneath the skin, or involve deeper tissues, and can affect the face, lower extremities, or spinal column. When found in association with multiple discrete neurofibromas, PN is virtually pathognomonic for NF1. The tumor is often disfiguring, and function may be com- promised by tumor size and/or neurovascular involvement. In contrast with sporadic localized neurofibromas, PNs associ- ated with NF1 tend to be larger, multiple, and involve deep nerves. 2–4 We report the finding of PN in two of seven patients from three generations of a family with NF1. Patient and Methods A 22-year-old man (proband) presented with a 2-year history of disfiguring, gradually progressive, but asymptomatic, swelling of the right side of the forehead. He also noted pea- to walnut-sized skin lesions elsewhere on the body. Asymptomatic and progressive areas of cutaneous pigmentation in these lesions had been observed since birth. The proband’s mother (age, 50 years), older brother (28 years), and sister (24 years) had the disease, as did the maternal grandmother (65 years), uncle (42 years), and aunt (40 years). In total, seven members of the family tree (Fig. 1) were affected. There was no history of consanguinity. Examination revealed multiple tumors varying in size from several millimeters to 0.5–1 cm with a few larger lesions (greater than 5 cm in diameter). These lesions involved the trunk, abdomen, extremities, and face, and were punctuated by café-au-lait macules. The tumors were sessile or pedunculated, located in the skin or subcutaneous tissue, with prominent herniation (button-holing) of deeper lesions. The right side of the forehead (Fig. 2) was erythematous, raised, and had a “bag of worms” quality on palpation. There was prominent freckling of the axillae and groin. The patient’s older brother also showed extensive involvement of the trunk and extremities. A large PN was located on the chest. General physical examination, with attention to the eyes and bones, was unremarkable. The white blood cell