Itching syndrome as the only manifestation of neuropathic pain - A case report

Itch is a common manifestation in systemic disease. Recent microneurography studies showed that itch is mediated by a functionally distinct subset of C-fibres. We described the case of a 68-year-old woman complaining of itch at trunk and legs with acute onset three years before our first observation. Itch was induced by ambient warmth and was associated with a persisting burning-like heat sensation. Extensive dermatologic and allergologic investigations were negative. Treatment with antihistaminergic and low-dosage oral steroids for 6 months did not modify the clinical picture. Physical examination was negative. Laboratory investigations revealed only neutrophilic leukocytosis, whereas chemistry profile, thyroid-stimulating hormone, serum and urine immunofixation, and screening for immunologic, infectious, and neoplastic disease was negative. Cerebrospinal fluid examination was normal. Gabapentin (1200 mg/day) reduced itch severity from 10 to 5 of the visual analogue scale (VAS) at 1-month follow-up. Nerve conduction study and needle electromyography was normal. Quantitative sensory testing in foot and distal leg disclosed warm hyperalgesia. Cutaneous blood flow by laser Doppler flowmetry at distal legs showed abnormal vasodilatation function induced by local heating. Skin biopsy demonstrated reduced intraepidermal nerve fibre density at the proximal thigh (8.7/mm) and normal value at the distal leg (7.8/mm) with diffuse axonal swellings. Total body CT-scan showed laterocervical and mediastinic lymphadenopathy. The histological exam of axillary lymph nodes revealed T-lymphocitic T-zone lymphoma (TZL). Itch frequently occurs in lymphoproliferative disease. In our case we showed the histological impairment of small fibres suggesting the presence of uncommon Itching Small Fibre Neuropathy.