Measles: More than the rash (May 2016)

TO THE EDITOR: I read the excellent overview article on measles by Drs. Kumar and Sabella.¹ However, there are additional important clinical points regarding measles diagnosis that deserve further comment. Prior to definitive diagnosis, measles is a clinical diagnosis. Properly, much attention is given to the rash, but there are important clinical clues besides the rash that are helpful diagnostically.

Some clinical findings are more characteristic of a disease than others, eg, eye findings in measles, and clinicians should specifically look for them. Other findings not characteristic but consistent with the diagnosis are less helpful, eg, measles with diarrhea.² Measles is a systemic infection with several extradermatologic manifestations. Characteristically, measles involves the respiratory tract, manifested by runny nose, dry cough, or shortness of breath, ie, measles pneumonia.²

Gastrointestinal involvement may be manifested as nausea, vomiting, diarrhea, or abdominal pain. Abdominal pain, when located in the right lower quadrant, may mimic acute appendicitis, ie, pseudoappendicitis. In patients undergoing appendectomy, pathologically the appendix is normal but contains multinucleated giant cells (Warthin-Fin-keldey cells). Measles pseudoappendicitis can be perplexing because it presents before the rash. Even without appendiceal involvement (pseudoappendicitis), Warthin-Finkeldey cells are also present in the nasal mucosa. If nasal swab cytology shows Warthin-Finkeldey cells, an early diagnosis of measles may be made days before IgM measles antibodies are reported.³

Other often-overlooked important clues are eye findings, eg, watery eyes, lower lid edema, conjunctival suffusion, and keratitis. No other disease in the differential diagnosis of measles presents with watery eyes with bilateral lower lid edema and conjunctival suffusion. Headache, mental confusion or oral ulcers may suggest alternate diagnoses. Typically, nonspecific laboratory abnormalities include leukopenia and thrombocytopenia, and importantly, the erythrocyte sedimentation rate is not elevated (Table 1).^4,5

In measles, much is made of Koplik spots, which are found early on dark red buccal mucosa (vs Fordyce spots).¹ However, if these are missed or not present, clinicians can use other characteristic findings to make a presumptive diagnosis of measles.

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