SHM Converge Scientific Abstract ePoster Gallery-Methotrexate: Skin's Friend or Foe?

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This case describes an 80-year-old man with dementia and rheumatoid arthritis who developed a rapidly spreading maculopapular rash after a switch from subcutaneous to oral methotrexate (MTX) 20 mg weekly because of a medication shortage. The rash began on his back and spread to the chest, abdomen, neck, face, scalp, and arms. He also had fever, mucositis, and pancytopenia, raising concern for MTX toxicity.<br /><br />On admission, the patient had diffuse erythematous macules and papules with pustules, while the lower extremities were spared. Workup was negative for HSV, VZV, and blood cultures, though skin cultures grew Serratia and Klebsiella, suggesting concomitant bacterial skin infection. Despite the infections, the team concluded that MTX toxicity was the main cause of the rash, especially given the associated pancytopenia and mucosal involvement. His use of lansoprazole may also have reduced MTX elimination and increased toxicity risk.<br /><br />Treatment initially included broad antimicrobials: IV vancomycin, IV cefepime, IV acyclovir, and oral fluconazole. Acyclovir was stopped after HSV testing was negative, and vancomycin/cefepime were discontinued when blood cultures remained negative. The rash improved significantly by hospital day 10, and he was discharged with cefpodoxime and fluconazole, with rheumatology follow-up.<br /><br />Key teaching points are that MTX toxicity should be considered in any patient on methotrexate who develops a new rash, and that even changes in administration route—from subcutaneous to oral—can meaningfully alter adverse-effect risk. MTX can cause a nonspecific morbilliform rash in up to 15% of patients, and severe cases may progress to bullae or toxic epidermal necrolysis.

Asset Subtitle

Vineet Gupta

Meta Tag

Author List Justin Wong, MaryAnn Villarreal-Gonzale, Vineet Gupta

Category Clinical Vignettes

Concept Methotrexate Toxicity

Concept Mucositis

Concept Pancytopenia

Concept Methotrexate

Concept Toxic Epidermal Necrolysis

Distinguished Non-Finalist

Presenter Organization Ucsd

Presenting Author Vineet Gupta

Track Adult

Keywords

methotrexate toxicity

maculopapular rash

pancytopenia

mucositis

rheumatoid arthritis

oral methotrexate

subcutaneous to oral switch

drug eruption

elderly patient

skin infection

Methotrexate Toxicity

Mucositis

Pancytopenia

Methotrexate

Toxic Epidermal Necrolysis