Archives of Iranian Medicine, Volume 13, Number 3, May 2010253
A 54-year-old male smoker presented with com-
plaints of generalized bone and muscle pain. His
pain was aggravated over time to the extent that he
became unable to walk and developed paraparesis.
Upon physical examination, a tumor was not located,
however, generalized bony tenderness with decreased
muscle strength, predominantly in the lower extremi-
ties was noted. On lung examination, bilateral scat-
tered wheezing was heard.
The patient underwent a bone scan which revealed
multiple metabolically active bony lesions in the ribs
(mainly in the costochondral junctions), sternum, low-
er cervical and thoracic spine that was suspicious for
multiple bony metastases versus metabolic bone dis-
ease (Figure 1). Thoracolumbosacral magnetic reso-
nance imaging (MRI) results revealed hypersignal in-
tensity on T1 and T2 images that favored replacement
of red marrow with fat (Figure 2).
Imaging studies which included: spiral chest, ab-
dominopelvic, and paranasal CT-scans were unre-
Both bone and bone marrow biopsies to detect the
primary tumor location were normal (Figure 3). Se-
rum phosphate level was 1.8 mg/dL, urine phosphate
was 103mg/dL, and parathyroid hormone was within
the normal range.
The patient had an undetectable serum 1,25-dihy-
droxyvitamin D and severe osteomalacia per a dual
energy X-ray absorptiometry (DEXA) bone densi-
What is your diagnosis?
See the page 254 for diagnosis
Mehdi Dehghani MD1, Mohammad Hossein Dabaghmanesh MD2,
Golam Hossein Omrani MD2
Authors’ af?liations: 1Department of Hematology and Oncology,
Hematology Research Center, Shiraz University of Medical Sciences,
Shiraz, Iran. 2Endocrine and Metabolism Research Center, Shiraz
University of Medical Sciences, Shiraz, Iran.
Corresponding author and reprints: Mehdi Dehghani MD,
Department of Hematology and Oncology, Hematology Research
Center, Shiraz University of Medical Sciences, Shiraz, Iran. Fax:+98-
Figure 1. Bone scan of a 54-year-old man
Figure 2. Thoracolumbosacral MRI of the patient
Figure 3. Bone biopsy picture (H&E ×100)
Archives of Iranian Medicine, Volume 13, Number 3, May 2010 Download full-text
Oncogenic osteomalacia (OOM) is an interesting
subject that has preoccupied physicians for decades.
The traditional name for this disorder, OOM, implies
a paraneoplastic phenomenon, secondary to a tumor.
Such characterization is inaccurate, however, in that
the involved “neoplasm” is often (but not always)
of limited clinical signi?cance, apart from its causal
role in musculoskeletal disease. Tumors responsible
for OOM are usually benign rather than malignant;
whereas generalized debilitating osteomalacia
and rickets are important clinical problems for the
In OOM, a tumor produces an unknown substance
that inhibits phosphate reabsorption in the proximal
tubules. This causes urinary phosphate wasting and,
as a consequence, hypophosphatemic osteomalacia.2
Osteomalacia is associated with many clinical
(bone pain and weakness), radiographic (compression
fracture), and biochemical abnormalities (increased
Unfortunately, none of these are pathognomonic
for the disorder, and histological examination of a
bone biopsy specimen is often necessary to con?rm
the diagnosis. Noninvasive methods of diagnosis
would be preferable to decrease patient morbidity
and increase cost-effectiveness.3
Tumor-induced hypophosphatemic osteomalacia
is a syndrome characterized by urinary phosphate
wasting related to the presence of a slowly-growing
tumor of mesenchymal origin. The characteristic
laboratory ?ndings are normal serum calcium,
marked hypophosphatemia, increased serum alkaline
phosphatase, markedly reduced renal tubular
reabsorption of phosphorus and inappropriately low
levels of 1,25-dihydroxyvitamin D [1,25-(OH)2D].4
Because of the dif?culty in locating the primary
tumor, total body magnetic resonance imaging MRI,
octreotide scintigraphy, and PET/CT are helpful
Localization of the tumor site is an important
consideration in treating patients with OOM. The
clinical course is dramatically affected by tumor
removal and, if possible, is the treatment of choice.7,8
If the primary site can not be located or complete
tumor excision is not possible, treatment with high
doses of vitamin D or its potent derivatives and
phosphate supplements are recommended in patients
with hypophosphataemic osteomalacia. Treatment
with calcitriol (up to 3 mcg/day) and phosphate (2 –
4 g/day) will improve both osteomalacia and muscle
weakness. Metabolic balance studies have shown
the additional effect of calcium supplements during
the ?rst 4 – 6 months of healing.9
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