No abstract

Background: Erythromelalgia is a rare disease with increasing incidence. It manifests as episodic painful red extremities triggered by heat. External cooling provides temporary symptomatic relief but may lead to complications such as cellulitis. Management includes trigger control, behavioral therapy and pain management. Case Presentation: A 47-year-old African American male presented to the hospital with worsening bilateral lower extremity pain for three months. It was episodic, triggered by running and associated with erythema and swelling. Patient used cold water immersion and air conditioning for pain relief. One week prior to presentation, he developed painful blisters on his feet. On presentation, vital signs were stable, patient was afebrile. Acute infection was ruled out and he was discharged with outpatient rheumatology follow up for erythromelalgia. He returned one week later with worsening symptoms. CT scan of lower extremities indicated bilateral cellulitis. Patient was managed by medicine, dermatology, rheumatology, and podiatry for cellulitis, fungal infection, trench foot and primary erythromelalgia with antibiotics, antifungals, gabapentinoids and behavioral therapy. His infection resolved and pain improved. He was discharged with outpatient rheumatology follow up. Discussion: Erythromelalgia is a highly debilitating disease with episodes of burning erythematous extremities triggered by increase in skin temperature. Patients seek pain relief by excessive external cooling. Pathophysiology involves gain of function mutation in voltage gated sodium channels causing autoregulatory dysfunction of skin. Underlying disease mechanisms are ambiguous and may involve unidentified genetic components and unknown triggers. It is a clinical diagnosis. Therapy requires a multidisciplinary approach. Complications should be promptly addressed given attention next to symptomatic relief. There is a lack of disease specific treatment and complete remission is unlikely. Our patient responded well to gabapentinoids and behavioral therapy.

Methotrexate is a disease-modifying anti rheumatic drug (DMARD) that is often used in low dosages as the first line drug for rheumatoid arthritis patients. The chemotherapeutic agent works by inhibiting dihydrofolate reductase, and the primary route of clearance of the drug is via the kidneys. Kidney injury may delay this clearance and lead to toxic level accumulation of the drug-toxicity presenting as diarrhea, vomiting, mucositis, rash, transaminitis and myelosuppression. Antibiotics such as vancomycin may induce acute kidney injury (AKI) through various mechanisms include damage to the renal tubular epithelial cells. In this report, we describe a case in which an elderly female suffered AKI secondary to vancomycin induced nephrotoxicity. The AKI subsequently led to methotrexate accumulation and toxicity presenting as bleeding mouth ulcers, transaminitis and pancytopenia. The condition was managed with leucovorin rescue therapy and sodium bicarbonate to enhance methotrexate excretion. Renally dosing methotrexate in patients on other nephrotoxic drugs, and monitoring creatinine clearance are methods for preventing such a toxicity.