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Journal of Cancer Research and Therapeutics, Vol. 5, No. 3, July-September, 2009, pp. 210-212 Case Report Oncogenous osteomalacia Ghosh Soumitra, Sinha Ramanuj, Bandyopadhyay Ranjana, Malhotra Mainak Department of Pathology, Medical College, Kolkata, West Bengal Code Number: cr09052 PMID: 19841566 DOI: 10.4103/0973-1482.57130 Abstract Oncogenous osteomalacia is a rare paraneoplastic renal phosphaturic condition, often associated with highly vascular benign mesenchymal tumors. We report a case of a 48-year-old male who presented with debilitating osteomalacia unresponsive to standard therapy. Two years later, sinonasal hemangiopericytoma was diagnosed; the patient underwent complete surgical excision with rapid symptomatic improvement.Keywords: Oncogenous osteomalacia, sinonasal hemangiopericytoma Introduction Oncogenous osteomalacia is characterized by osteomalacia with hypophosphatemia, hyperphosphaturia, and undetectable or inappropriately low circulating concentrations of 1,25-dihydroxyvitamin D 3 , usually in patients with soft tissue mesenchymal tumors. [1] The exact prevalence has not been studied. [2] Case Report A 48-year-old male factory worker presented with progressive, diffuse, dull ache involving large joints of the body and low back ache along with weakness for 2 years. The pain used to get aggravated by activity and minimally relieved by rest and analgesics. Weakness initially involved both the lower limbs with proximal groups affected more than the distal and subsequently involved the upper limbs. There was no history of red hot joints, red eyes, diabetes, hypertension, tuberculosis, jaundice, promiscuous sexual exposure, visual symptoms, imbalance, and sphincteric or sensory abnormalities. He was treated with analgesics, oral calcium, and vitamin D. An examination of the motor system revealed poor nutrition, normal tone, power 2/5 in proximal muscles of all four limbs, and 4/5 in distal muscles. There was no involuntary movement, sensory, cerebellar signs, or trophic changes; reflexes were normal. Rest of the examination was noncontributory. Routine hemogram, renal function, thyroid function, and serum electrolytes were normal. Serum rheumatoid factor, antinuclear factor, and HLA-B27 were negative. A liver function test revealed very high alkaline phosphatase (1,366 IU; normal < 275 IU) with other parameters being normal. Serum ionized calcium was 4.7 mg/dl (normal 4.3-5.6), inorganic phosphorus 1.65 mg/dl (normal 3-4.5), parathyroid hormone 19.6 pg/ml (normal 12-72), 25-hydroxy vitamin D 3 37.7 ng/ml (normal 15-80), and 1,25-dihydroxy vitamin D 3 12.6 pg/ml (normal 25-45). A bone scan showed generalized osteopenia and decreased vertebral body height. A skeletal survey showed marked osteopenia, a reduction in the vertical height of vertebral bodies, and the presence of pseudofractures (Looser′s zone) above the acetabuli of pelvic bones [Figure - 1]. Serum protein electrophoresis was normal. A diagnosis of osteomalacia was made and the patient was given oral calcium 1,000 mg per day along with calcitriol 0.5 mcg. Over next few weeks, the serum alkaline phosphatase level decreased without any change in phosphate or clinical symptoms. The estimation of daily urinary phosphate excretion showed an elevated value (2,440 mg/day; normal 400-1300) while calcium excretion was normal. A primary renal phosphaturic condition was suspected. Oral phosphate (1.2 g per day) was added and the daily dose of oral calcium was increased to 2 g. However, there was little change in clinical or biochemical parameters and the patient was lost in follow-up. Two years later, the patient again presented in an incapacitated, bed-bound state with new onset nasal stuffiness and intolerable frontal headache. An X-ray of paranasal sinuses showed mucosal thickening. The patient had one episode of profuse epistaxis and had to be admitted. Nasal endoscopy revealed a mass in the left nasal cavity and nasopharynx, encroaching up to the middle meatus. A contrast-enhanced computed tomography (CECT) scan showed an enhancing mass almost filling the nasopharynx [Figure - 2]. Magnetic resonance imaging (MRI) demonstrated the brightly enhancing nasopharyngeal tumor with an extension along the left inferior turbinate [Figure - 3]. CECT of the thorax and ultrasonography (USG) of the abdomen were unrevealing. A lateral rhinotomy was done and histopathology of the excised mass showed hemangiopericytoma (HPC)---sinonasal type [Figure - 4]. Postoperatively, serum alkaline phosphatase progressively declined (from 2,476 IU to 426 IU within 3 months). The patient was able to walk within 1 month of operation, and joined his office within 3 months. Discussion HPCs are rare mesenchymal tumors originating from extravascular pericytes that account for 3-5% of all soft tissue sarcomas, and 1% of all vascular tumors. [2] Some 15-30% of all HPCs occur in the head and neck; of these, approximately 5% arise in the sinonasal area. [2] Epistaxis and obstructive respiratory symptoms are the usual presenting complaints. [3] Plain radiographs are of limited diagnostic value. [4] CT clearly demonstrates tumor involvement of soft tissues that typically enhance after contrast administration, and bone destruction with large lesions. [4] On T1-weighted MRI, they appear as solid isointense masses with diffuse enhancement after gadolinium; on T2-weighted imaging, they reflect isointense to low-intensity signals. MRI helps in differentiating the tumor tissue from the inflammatory fluid caused by sinus obstruction and is the best means of demonstrating tumor extension to the skull base. [2] An aggressive surgical approach, often by the combined external-endodasal route, is recommended but there is a high chance of recurrence. [5] Oncogenous osteomalacia is a rare syndrome characterized by osteomalacia with hypophosphatemia, hyperphosphaturia, and undetectable or inappropriately low circulating concentrations of 1,25-dihydroxy vitamin D 3 usually in patients with soft tissue mesenchymal tumors. [1] The head and neck region is a frequent site of these tumors, and the mean time taken for diagnosis is 4.5 years. [6] Hypophosphatemia, associated with a fall in plasma levels of 1, 25 dihydroxy vitamin D 3 by an inhibition of renal 1 α hydroxylase, suggests the existence of a complex tubular defect. [1] Expression of fibroblast growth factor-23 (FGF-23), a recently described protein putatively implicated in renal tubular phosphate loss, has been shown in a small number of mesenchymal tumors with known oncogenous osteomalacia. [7] Tumor removal results in rapid normalization of laboratory, radiological, and clinical abnormalities. [1] Thus any case of hypophosphatemic osteomalacia requires investigation for a possible tumor of connective tissue. Our patient presented with bone pain and predominantly proximal muscle weakness and a diagnosis of hypophosphatemic osteomalacia was made that was poorly responsive to standard therapy. Finally, the characteristic soft tissue neoplasm was detected 4 years from the onset of his symptoms. References
Copyright 2009 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr09052f2.jpg] [cr09052f4.jpg] [cr09052f1.jpg] [cr09052f3.jpg] |
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