This patiënt has been suffering from cramps and myalgia for many years. X-ray of her hand revealed complete destruction of the third metacarpal bone. What could be the underlying condition? I’ll post the correct answer in about three days!
Correct answer: Tumor induced osteomalacia. In this case, the tumor produced FGF-23, leading to hypophosphatemia (causing cramps) and mineralisation deficiency. Twenty years later, the third metacarpal bone was completely destroyed.
Summary of Tumor induced Osteomalacia What is 'Tumor induced Osteomalacia' ? It's a paraneoplastic syndrome, mediated by FGF23 (mainly), frizzled-related protein 4 and matrix extracellular phosphoglycoprotein (MEPE), secreted by mainlt benign tumors such as - mesenchymal or mixed connective tissue tumor (usually phosphaturic mesenchymal tumor and hemangiopericytoma) and some malignant tumors ( very rarely ) such as - osteosarcoma and fibrosarcoma. Symptoms Adult patients have worsening myalgias, bone pains and fatigue which are followed by recurrent fractures. Children present with difficulty in walking, stunted growth and deformities of the skeleton (features of rickets). Pathogenesis FGF23 (fibroblast growth factor 23) inhibits phosphate transport in the renal tubule and reduces calcitriol production by the kidney. Tumor production of FGF23, frizzled-related protein 4 and matrix extracellular phosphoglycoprotein (MEPE)have all been identified as possible causative agents for the hypophosphatemia. Remember - Phosphate in addition to being imp in bone mineralization is very imp to muscle as it is an imp component of ATP and is imp to keep glucose within muscle in the form of Glucose 6 PO[SUB]4[/SUB] Diagnosis Biochemical studies reveal hypophosphatemia, elevated alkaline phosphatase and low serum 1, 25 dihydroxyvitamin D levels. Routine laboratory tests do not include serum phosphate levels and this can result in considerable delay in diagnosis. Locating the tumor can prove to be difficult and may require whole body MRI. Some of the tumors express somatostatin receptors and may be located by octreotide scanning. Differential diagnosis Serum chemistries are identical in tumor-induced osteomalacia, X-linked hypophosphatemic rickets (XHR) and autosomal dominant hypophosphatemic rickets (ADHR). A negative family history can be useful in distinguishing tumor induced osteomalacia from XHR and ADHR. If necessary, genetic testing for PHEX (phosphate regulating gene with homologies to endopepetidase on the X-chromosome) can be used to conclusively diagnose XHR and testing for the FGF-23 gene will identify patients with ADHR. Treatment Resection of the tumor is the ideal treatment and results in correction of hypophosphatemia (and low calcitriol levels) within hours of resection. Resolution of skeletal abnormalities may take many months. If the tumor cannot be located, treatment with calcitriol (1-3 µg/day) and phosphorus (1-4 g/day in divided doses) is instituted. Tumors which secrete somatostatin receptors may respond to treatment with octreotide. If hypophosphatemia persists despite calcitriol and phosphate supplementation, administration of cinacalcet has been shown to be useful. ref - majority of the matter is from - Tumor-induced osteomalacia - Wikipedia, the free encyclopedia Why did I evoke / revive this thread again ? I had given a talk on 'Pain' in December and in attendance were a lot of people with unresolved pain issues ( understandably ) and I could pin the cause ( predominantly biomechanical issues and some neurological ) and could help the majority of them. But there was a subset which was very intriguing - no diabetes, no hypothyroidism, normal LFTs and Kidney function, serum calcium on the lower side of normal. So i asked for Dexa scan, urine Calcium, Chest X ray, Mamography, Colonoscopy, screening Abd USG and PSA, wherever appropriate. Most haven't reported back yet....which could mean that either they have done the tests and the reports are normal or they were faking their symptoms ( and so didn't feel the need to undergo the tests ) or have gone for alternative therapy or have decided to put all their trust in God ( which is not a bad option P: ). Some of whom who came back, had everything within the normal range ( except for one patient who had endometriosis as a cause of her back pain) and so I was thinking about fibromyalgia and myofascial causes in the rest ( about which I know very little ). I know how to do a detailed posture and gait analysis, detect muscle imbalances precisely and can suggest remedial stretching of chronically contracted muscles ( ex. pec major,hamstrings, psoas major and quadratus lumborum in those who r always on the desk ) and contracting / increasing tone in chronically stretched out muscles ( ex. rhomboids and errector spinae )...but myofascial and trigger points is beyond my scope to detect. The only thing I missed in everybody is asking for serum PO[SUB]4[/SUB] . Thanks to this thread, I will ask for it form now on, whenever i ask for calcium. Alk PO4 can throw some very confounding results and so i generally don't ask for it. Thanks to JC Peper for posting this challenge and credit to everybody who got this correct. Let's hope this diagnosis remains at a concious level and we may be able to help some of our patients with 'pain of unknown origin' abrreviated as P wink) O, for whom 'Tumor induced Osteomalacia' may be the cause , rather than instinctively label them as being stressed and having fibromyalgia ( just like we label many patients with 'GI distress of unknown origin' as having 'IBS' ...imagine somebody who gets this diagnosis ? won't he have Irritable bowels from the on :hhh: ) Signing off (Y)
