A case of systemic mastocytosis (SM) in which recurrent vertebral fractures were the primary symptom was recently illustrated in a case report published in the Journal of the Endocrine Society.
SM can cause secondary osteoporosis and fragility fractures. Since SM is usually associated with gastrointestinal, allergic and skin symptoms, however, healthcare providers might not suspect SM is to blame in cases where osteoporosis is the main symptom.
In this case report, the authors illustrated how SM may masquerade as more common metabolic bone disorders and highlight the diagnostic value of serum tryptase in unexplained cases of osteoporosis.
Read more about SM testing and diagnosis
The case involved a 56-year-old man whose first fracture occurred in 2016 while he was jumping on a trampoline. The man noted he had hot flashes, fatigue and decreased muscle strength; it was found he had low testosterone levels, which can increase osteoporosis risk. Despite being started on testosterone replacement therapy, however, he continued to experience symptoms.
A year later, without any traumatic event, he developed a new vertebral fracture. The patient was prescribed anti-resorptive therapy with ibandronate and later risendronate — medications used to treat osteoporosis — but stopped taking these after two years.
The patient subsequently sustained additional fractures. One fracture followed a fall from standing height, but required a lumbar fusion and other surgeries.
A broad evaluation for secondary causes of osteoporosis initially failed to yield any abnormalities. The patient had a history of intermittent glucocorticoid use for back pain, but this alone did not explain the severity and progression of his bone disease.
Further investigation, prompted by the patient’s persistent hot flashes and subtle laboratory abnormalities, revealed markedly elevated serum tryptase levels on three separate occasions. A referral to immunology led to a bone marrow biopsy, which confirmed the diagnosis of smoldering systemic mastocytosis (SSM), a variant of SM characterized by mast cell infiltration without full-blown systemic symptoms.
Following diagnosis, the patient was treated with anabolic therapy (teriparatide), followed by zoledronic acid, and subsequently enrolled in a clinical trial for SSM.
“Screening with serum tryptase should be considered in an adult with osteoporosis and pathologic bone fractures if no other risk factors for osteoporosis are identified or if other complementary features are present,” the authors wrote.
Sign up here to get the latest news, perspectives, and information about SM sent directly to your inbox. Registration is free and only takes a minute.
