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Herrick J. Siegel, MD, University
of Alabama at Birmingham; Michael G. Rock, MD, Franklin H.
Sim, MD, Carrie Inwards, MD, Mayo Clinic
The delay in diagnosis of an
occult tumor causing osteomalacia can often lead to unnecessary
treatment and progression of the disease causing severe debilitation
of the patient. The oncogenic cause of osteomalacia is often
unrecognized because the tumors are frequently very small
and may be osseous or in the soft tissues. We evaluate the
methods used to reach the diagnosis, the length of time between
presentation and diagnosis, and long-term follow-up after
tumor resection. The medical records and pathology of 19 patients
treated at the Mayo Clinic for oncogenic osteomalacia between
1965 and 2001 were reviewed. Eight women and 11 men with an
age range of 27 to 68 years of age. Follow-up ranged from
2-27 years (average: 8 years). In all cases laboratory values
improved to within normal limits within 6 months post-resection.
The delay in diagnosis ranged from 18 months to 14 years (average:
3.8 years). Nine of the 10 (90%) sustained an insufficiency
fracture by the time of diagnosis. The lesions were detected
by skeletal survey in 5 cases, radionuclide scan in 8 cases,
CT scan in 2 cases and MRI in 4 cases. The delay in diagnosis
were most commonly related to suspicion of alternative causes
of osteomalacia. Oncogenic osteomalacia is a rare clinicopathologic
syndrome characterized by mesenchymal tumors that produce
osteomalacia and biomechanical abnormalities consisting of
hypophosphatemia, normocalcemic, and increased levels of alkaline
phosphatase. The delay in diagnosis usually leads to years
of disability, progressive extremity deformity and multiple
stress fractures. The dramatic improvement of both clinical
and laboratory features of the disease makes the identification
of the inducing tumor crucial. A high level of suspicion is
necessary, if a patient is refractory to medical treatment
and body MRI or radionuclide scanning is recommended for early
detection.
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