What’s Your Diagnosis?

A Tender Nodule © Simon K. Lee, MD, FRCPC right ibution py istr ad, Co l D ownlo A 30-year-old woman complains of a long - rcia can d me users use standing lesion on her foot of over 1o0-ymears orised sonal r C . Auth or per duration. It has progreessiv eoly enlahrigbeidt eodver copy f Sal se pro ingle for ised u rint a s timoe tan d recaeuntlhy obrecome pain fauln du pe to inci - N Un y, view dental trauma. Edxiasmpilnaation reveals a 1 cm flesh coloured, smooth, dome-shaped nodule on the dorsum of her right foot. What is your diagnosis? a. Keratoacanthoma b. Basal cell carcinoma c. Chondrodermatitis nodularis helicis malignant trasformation. Dermal NF may also d. Solitary neurofibroma be subdivided into three types depending on e. Pyogenic granuloma depth of location: superficial cutaneous, der - Answer: Solitary neurofibroma mal/nodular, and subcutaneous NF. Lesions often develop during teenage years. Neurofibromas (NF) represent benign prolifer - It is postulated that there is loss of control of the ation of the nerve sheath cells (nonmyelinating NF1 gene that codes for the nerve protein neu - Schwann cells) in the peripheral nervous rofibromin leading to loss of tumour suppressor system. They may occur randomly in a soli- function. Several mechanisms (two-hit hypoth - tary fashion or present with multiple lesions esis) are required to result in cellular hyperpla - in patients with the genetic condition of sia leading to neurofibroma formation. neurofibromatosis. The astute clinician may make the diagnosis Solitary neurofibromas may occur anywhere based on examination. Definitive diagnosis and on the body and are often asymptomatic. treatment requires surgery. MRI may aid in the However, as they enlarge in size, progressive the diagnosis and monitoring of lesions. pain and dysesthesia may arise due to displace - The majority of lesions are simply excised ment and compression of local structures. successfully with relief of symptoms. Difficult Tapping on large lesions may result in discom - cases may require microscopic assessment and fort radiating along the distribution of the intraoperative electrophysiological monitoring involved nerve. Significant morbidity may in order to preserve functional nerve fascicle in develop with paraspinal lesions. larger lesions. A nerve graft may also be need - Solitary neurfibroma may arise from a single ed to avoid paralysis, dysesthesia, and pain. D peripheral nerve (dermal) or multiple nerve x sheaths (plexiform). More importantly, plexi - Dr. Simon K. Lee is a Dermatologist in Richmond Hill, form neurofibromas have up to a 10% risk for Ontario.

The Canadian Journal of Diagnosis / December 2012 33