Case Report
Indolent Systemic Mastocytosis as the Cause of a Long History of Unexplained Hypotensive Episodes
Abstract
Assessment of patients with unexplained hypotensive episodes in outpatient practice is often challenging, with an extensive differential diagnosis. The prevalence of systemic mast cell disease (MCD) is unknown, and the diagnosis is often elusive because serum and urine markers may become positive only after one of the self-limited, recurrent hypotensive episodes. Nevertheless, MCD is increasingly recognized as a cause of unexplained hypotension, secondary osteoporosis, and anaphylactic reactions to Hymenoptera stings. We describe a 38-year-old man who had a 15-year history of undiagnosed, recurrent hypotensive episodes with stereotypic symptoms. Extensive evaluation during these years was unrevealing. On physical examination, he appeared to be a healthy man with a prominent macular rash. Results of skin biopsy showed tryptase-positive mast cells. He had markedly elevated serum tryptase levels, and results of bone marrow biopsy revealed 10% mast cells; all these findings were consistent with indolent systemic mastocytosis. Key features in his history and physical examination prompted the conclusive testing. The most telling features were hypotension, tachycardia, and the rash (urticaria pigmentosa).
Key Points
* Systemic mastocytosis is a cause of unexplained hypotension with stereotypic, self-limited, recurrent symptoms; it may have unpredictable triggers and is difficult to diagnose.
* To diagnose mastocytosis, the clinician must remain alert for characteristic features during the history and physical examination and inform the pathologist if mast cell disease (MCD) is suspected.
* Measurement of serum tryptase levels is a more useful diagnostic test than the formerly used 24-hour urine collection for histamine.
* Mast cell disease should be considered in patients with stereotypic, self-limited, recurrent symptoms, anaphylactic-like episodes, and secondary osteoporosis.
* Symptomatic treatment is available, and patients with untreated MCD may have significant morbidity.
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