Super Scan Leading to Definitive Diagnosis in a Patient With Recurrent Syncope

A "super scan" pattern detected on bone scintigraphy usually indicates either metabolic bone disease or diffuse metastases. We report a rare case of a 45-year-old man with recurrent episodes of syncope of 10 years' duration in whom bone scintigraphy showed a super scan with an axial skeleton distribution of uptake. Bone marrow biopsy established the diagnosis of systemic mastocytosis. The few reports in the literature of super scans associated with systemic mastocytosis showed diffuse axial and appendicular increased uptake. The present case shows a super scan involving the axial skeleton, which led to the diagnosis of systemic mastocytosis.

Systemic mastocytosis

Mastocytosis is a disease characterized by an abnormal increase in mast cells. Rare in occurrence, protean in its manifestations, it is a disease which is very seldom thought of and hence, possibly even overlooked. The last few decades have witnessed an upsurge in the understanding of the physiology and pathobiology of mast cells. Better means for diagnosis and follow-up have become available. Once a diagnosis is established histamine antagonists remain the mainstay of treatment. Most patients live and die with the disease rather than of it. The objective of this review is to discuss this entity with a special focus on diagnosis and treatment.

Response of severe systemic mastocytosis to interferon alpha

Six patients with documented systemic mast cell disease were enrolled in a 1-year, phase I study to determine the possible benefits of interferon alpha-2b (IFN-alpha). IFN-alpha therapy was begun at a dosage of 0.5 million units/day (MU/day) by subcutaneous injection and increased, as tolerated, to 3.0 MU/day. Subsequent dose modifications were made based on clinical tolerance and response. No immediate, adverse reactions to IFN-alpha occurred. Several patients showed symptomatic improvement. In two patients ascites resolved and did not recur. Two other patients reported improved energy levels and had decreased size of retroperitoneal, measenteric and retrocrural nodes. One patient failed to benefit and died shortly after completing 12 months of therapy. Bone marrow mastocytosis decreased by 5% to 10% after 12 months of therapy with IFN-alpha. Although five of the six patients had a decrease in the urinary excretion of 1-methyl-4-imidazole acetic acid, serum tryptase values did not appreciably change in any patient. Side-effects from IFN-alpha included hypothyroidism, thrombocytopenia and depression. It is concluded that although treatment with IFN-alpha was associated with a decline in bone marrow mastocytosis and reduced excretion of histamine metabolites, prolonged therapy may be needed and dose-limiting side-effects are frequent.

Mastocytosis

Mastocytosis implies involvement by excessive numbers of mast cells, of skin and/or other organs. Symptoms may be absent to severe, even occasionally life-threatening. H1- and H2-blocking agents potentially may relieve symptoms, but do nothing to prevent systemization. At present no specific combination chemotherapy regimen has been shown to be markedly effective in a large controlled study. Mithramycin may be of benefit in relieving localized bone pain, although confirmation of this observation in large numbers of patients is needed. PUVA may be a viable approach to symptomatic treatment of otherwise poorly controlled urticaria pigmentosa. In children, urticaria pigmentosa is a relatively benign disease without an increased risk of later systemic involvement. In adults, however, other organs by be involved, with resultant increased morbidity and mortality. Without specific symptoms to a particular organ system, elaborate and expensive staging work-up is not indicated, at least until there is evidence that a reproducibly effective therapy for systemic disease exists.