History: This 64 yo business man has experienced dysesthesia on the lateral aspect of his left thigh for the past few years. He has noticed alopecia at the site of his symptoms. His health is good and he takes no medications by mouth. For the past 30 years, he has done business in Indonesia and spends two to three months a year there. There is a history of lower back pain, but no diabetes and no history of trauma.
O/E: On the left lateral thigh there is a side, 7 cm in diameter area of mild lichenification and alopecia. The findings are subtle but real. I am not sure how convincing the photos are.
Clinical Photos:
IMPRESSION: This is most likely merlagia paresthetica.
Questions:
The findings are subtle. Do you accept this diagnosis? Would a referral to a neurologist be appropriate? Should the patient just be reassured?
References:
1. Nabavi DG, et. al.. [Meralgia paresthetica. A rare differential diagnosis of circumscribed alopecia] Dtsch Med Wochenschr. 1996 Jun 21;121(25-26):834-8. ([Article in German])
Klinik und Poliklinik für Neurologie, Universität Münster.
Abstract
HISTORY AND CLINICAL FINDINGS: Two patients with circumscribed alopecia on the lateral aspect of the thigh underwent a neurological investigation after medical and dermatological examinations had failed to establish the cause. Patient 1 also had neuralgia of the genitofemoral nerve after osteotomy of the iliac crest; patient 2 had insulin-dependent diabetes mellitus. Within the affected part of the skin both patients had sensory dysfunctions over the area of distribution of the cutaneous lateral femoral nerve. Patient 2 additionally had sensory dysfunctions in other areas of innervation. INVESTIGATIONS: Neurogram and recordings of sensory evoked potentials revealed decreased amplitudes on the affected side, establishing the diagnosis of meralgia paresthetica. TREATMENT AND COURSE: The painful neuropathy was successfully treated in both patients with carbamazepine (patient 1: 1.600 mg daily; patient 2: 900 mg daily). CONCLUSION: Circumscribed alopecia can be caused by peripheral nerve lesions. It should be considered in the differential diagnosis, particularly as the cause can be easily established.
2. Harney D, Patijn J. Meralgia paresthetica: diagnosis and management strategies. Pain Med. 2007 Nov-Dec;8(8):669-77.
Department of Anesthesiology and Pain Management, University Hospital Maastricht, Maastricht, The Netherlands. dharney@hotmail.com
Abstract
Meralgia paresthetica (MP), coined from the Greek words meros (thigh and algos), meaning pain, is a neurological disorder characterized by a localized area of paresthesia and numbness on the anterolateral aspect of the thigh. The incidence of MP is more common than often reported in the literature. The etiology of MP includes mechanical factors such as obesity, pregnancy, and other conditions associated with increased intrabdominal pressure, surgery of the spine, and pelvic osteotomy. A coherent history and pertinent physical examination is essential in making the diagnosis; however, red flags such as tumor and lumbar disk herniations must be recognized and appropriately treated. While the diagnosis of MP is essentially a clinical diagnosis, sensory nerve conduction velocity studies are a useful adjunctive diagnostic tool. The management of MP includes treating the underlying cause (if any) and conservative management. Surgery should only be adopted when all nonoperative therapies have failed to manage the condition in an effective manner.
Addendum: The history of spending time in Bali for the past 30 years made me consider tuberculoid leprosy -- but the findings are very subtle and there is no hypopigmentation. Sensation is abnormal in his patch, but present. Still... if this were Bali, or India perhaps we would do a bx -- maybe I should.
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