Phosphorus excretion in tumoral calcinosis: response to parathyroid hormone and acetazolamide

Congenital Hyperphosphatemic Conditions Caused by the Deficient Activity of FGF23

Congenital diseases that could result in hyperphosphatemia at an early age include hyperphosphatemic familial tumoral calcinosis (HFTC)/hyperostosis-hyperphosphatemia syndrome (HHS) and congenital hypoparathyroidism/pseudohypoparathyroidism due to the insufficient activity of fibroblast growth factor (FGF) 23 and parathyroid hormone. HFTC/HHS is a rare autosomal recessive disease caused by inactivating mutations in the FGF23, UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3), or Klotho (KL) genes, resulting in the excessive cleavage of active intact FGF23 (FGF23, GALNT3) or increased resistance to the action of FGF23 (KL). Massive ectopic calcification, known as tumoral calcinosis (TC), is seen in periarticular soft tissues, typically in the hip, elbow, and shoulder in HFTC/HHS, reducing the range of motion. However, other regions, such as the eye, intestine, vasculature, and testis, are also targets of ectopic calcification. The other symptoms of HFTC/HHS are painful hyperostosis of the lower legs, dental abnormalities, and systemic inflammation. Low phosphate diets, phosphate binders, and phosphaturic reagents such as acetazolamide are the treatment options for HFTC/HHS and have various consequences, which warrant the development of novel therapeutics involving recombinant FGF23.

Hyperphosphatemic familial tumoral calcinosis secondary to fibroblast growth factor 23 (FGF23) mutation: a report of two affected families and review of the literature

Hyperphosphatemic familial tumoral calcinosis (HFTC), secondary to fibroblast growth factor 23 (FGF23) gene mutation, is a rare genetic disorder characterized by recurrent calcified masses. We describe young Lebanese cousins presenting with HFTC, based on a retrospective chart review and a prospective case study. In addition, we present a comprehensive review on the topic, based on a literature search conducted in PubMed and Google Scholar, in 2014 and updated in December 2017. While the patients had the same previously reported FGF23 gene mutation (homozygous c.G367T variant in exon 3 leading to a missense mutation), they presented with variable severity and age of disease onset (at 4 years in patient 1 and at 23 years in patient 2). A review of the literature revealed several potential patho-physiologic pathways of HFTC clinical manifestations, some of which may be independent of hyperphosphatemia. Most available treatment options aim at reducing serum phosphate level, by stimulating renal excretion or by inhibiting intestinal absorption. HFTC is a challenging disease. While the available medical treatment has a limited and inconsistent effect on disease symptomatology, surgical resection of calcified masses remains the last resort. Research is needed to determine the safety and efficacy of FGF23 replacement or molecular therapy, targeting the specific genetic aberration. Hyperphosphatemic familial tumoral calcinosis is a rare genetic disorder characterized by recurrent calcified masses, in addition to other visceral, skeletal, and vascular manifestations. It remains a very challenging disease.

Dialysis as a Treatment Option for a Patient With Normal Kidney Function and Familial Tumoral Calcinosis Due to a Compound Heterozygous FGF23 Mutation

Primary tumoral calcinosis is a rare autosomal recessive disorder characterized by ectopic calcified tumoral masses. Mutations in 3 genes (GALNT3, FGF23, and KL) have been linked to this human disorder. We describe a case of a 28-year-old man with a history of painful firm masses over his right and left gluteal region, right clavicle region, knees, and left elbow. Biochemical analysis disclosed hyperphosphatemia (phosphate, 9.0 mg/dL) and normocalcemia (calcium, 4.8 mg/dL), with normal kidney function and fractional excretion of phosphate of 3%. Parathyroid hormone was suppressed (15 pg/mL), associated with a low-normal 25-hydroxyvitamin D (26 ng/mL) concentration but high 1,25-dihydroxyvitamin D concentration (92 pg/mL). Serum intact FGF-23 (fibroblast growth factor 23) was undetectable. Genetic analysis revealed tumoral calcinosis due to a compound heterozygous mutation in FGF23, c.201G>C (p.Gln67His) and c.466C>T (p.Gln156*). Due to lack of other treatment options and because the patient was facing severe vascular complications, we initiated a daily hemodialysis program even in the setting of normal kidney function. This unusual therapeutic option successful controlled hyperphosphatemia and reduced metastatic tumoral lesions. This is a report of a new mutation in FGF23 in which dialysis was an effective treatment option for tumoral calcinosis with normal kidney function.

Phenotypic and Genotypic Characterization and Treatment of a Cohort With Familial Tumoral Calcinosis/Hyperostosis-Hyperphosphatemia Syndrome

Familial tumoral calcinosis (FTC)/hyperostosis-hyperphosphatemia syndrome (HHS) is a rare disorder caused by mutations in the genes encoding fibroblast growth factor-23 (FGF23), N-acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO. The result is functional deficiency of, or resistance to, intact FGF23 (iFGF23), causing hyperphosphatemia, increased renal tubular reabsorption of phosphorus (TRP), elevated or inappropriately normal 1,25-dihydroxyvitamin D3 (1,25D), ectopic calcifications, and/or diaphyseal hyperostosis. Eight subjects with FTC/HHS were studied and treated. Clinical manifestations varied, even within families, ranging from asymptomatic to large, disabling calcifications. All subjects had hyperphosphatemia, increased TRP, and elevated or inappropriately normal 1,25D. C-terminal FGF23 was markedly elevated whereas iFGF23 was comparatively low, consistent with increased FGF23 cleavage. Radiographs ranged from diaphyseal hyperostosis to massive calcification. Two subjects with severe calcifications also had overwhelming systemic inflammation and elevated C-reactive protein (CRP). GALNT3 mutations were identified in seven subjects; no causative mutation was found in the eighth. Biopsies from four subjects showed ectopic calcification and chronic inflammation, with areas of heterotopic ossification observed in one subject. Treatment with low phosphate diet, phosphate binders, and phosphaturia-inducing therapies was prescribed with variable response. One subject experienced complete resolution of a calcific mass after 13 months of medical treatment. In the two subjects with systemic inflammation, interleukin-1 (IL-1) antagonists significantly decreased CRP levels with resolution of calcinosis cutis and perilesional inflammation in one subject and improvement of overall well-being in both subjects. This cohort expands the phenotype and genotype of FTC/HHS and demonstrates the range of clinical manifestations despite similar biochemical profiles and genetic mutations. Overwhelming systemic inflammation has not been described previously in FTC/HHS; the response to IL-1 antagonists suggests that anti-inflammatory drugs may be useful adjuvants. In addition, this is the first description of heterotopic ossification reported in FTC/HHS, possibly mediated by the adjacent inflammation. © 2016 American Society for Bone and Mineral Research.

Hyperphosphatemic familial tumoral calcinosis: genetic models of deficient FGF23 action

Hyperphosphatemic familial tumoral calcinosis (hFTC) is a rare disorder of phosphate metabolism defined by hyperphosphatemia and ectopic calcifications in various locations. To date, recessive mutations have been described in three genes involving phosphate metabolism: FGF23, GALNT3, and α-Klotho, all of which result in the phenotypic presentation of hFTC. These mutations result in either inadequate intact fibroblast growth factor-23 (FGF23) secretion (FGF23 or GALNT3) or resistance to FGF23 activity at the fibroblast growth factor receptor/α-Klotho complex (α-Klotho). The biochemical consequence of limitations in FGF23 activity includes increased renal tubular reabsorption of phosphate, hyperphosphatemia, and increased production of 1,25-dihydroxyvitamin D. The resultant ectopic calcifications can be painful and debilitating. Medical treatments are targeted toward decreasing intestinal phosphate absorption or increasing phosphate excretion; however, results have been variable and generally limited. Treatments that would increase FGF23 levels or signaling would more appropriately target the genetic etiologies of this disease and perhaps be more effective.

Hyperphosphatemic familial tumoral calcinosis: odontostomatologic management and pathological features

BACKGROUND

Hyperphosphatemic familial tumoral calcinosis (HFTC) is to a rare autosomal recessive disorder characterized by cutaneous and sub-cutaneous calcified masses, usually adjacent to large joints. The aim of the current study was to report on the clinico-pathological features of a patient with HFCT, with emphasis on alterations in the jawbones and teeth and the subsequent therapeutic interventions.

CASE REPORT

A 13-year-old male patient with HFTC diagnosis came to our attention for dental anomalies and maxillary and mandibular hypoplasia. OPT highlighted multiple impacted teeth, short and bulbous teeth, and pulp chamber and canal obliterations. Lateral cephalometric radiograms pointed out retrusion of both jaws, skeletal class II malocclusion, and deep-bite. He underwent orthopedic, orthodontic, conservative, and surgical treatments, allowing the correction of maxillo-facial and dental abnormalities and dysmorphisms without adverse effects. The surgical samples were sent for conventional and confocal laser scanning microscope (CLSM) histopathological examination, which highlighted several metaplastic micro- and macro-calcifications in the soft tissues, and typical islands of homogenous, non-tubular, dentino-osteoid calcified structures in dentinal tissues.

CONCLUSIONS

The management of maxillo-facial abnormalities in patients affected by HFTC is very difficult and, requires a combined therapeutic approach. To date, very few indications have been published in the literature.

Review of tumoral calcinosis: A rare clinico-pathological entity

Tumoral calcinosis (TC) has long been a controversial clinico-pathological entity. Its pathogenesis and genetic background have been gradually unravelled since its first description in 1943. According to the presence or absence of an underlying calcifying disease process, TC has been divided into primary and secondary varieties. Two subtypes of the primary variety exist; a hyper-phosphatemic type with familial basis represented by mutations in GalNAc transferase 3 gene (GALNT3), KLOTHO or Fibroblast growth factor 23 (FGF23) genes, and a normo-phosphatemic type with growing evidence of underlying familial base represented by mutation in SAMD9 gene. The secondary variety is mainly associated with chronic renal failure and the resulting secondary or tertiary hyperparathyroidism. Diagnosis of TC relies on typical radiographic features (on plain radiographs and computed tomography) and the biochemical profile. Magnetic resonance imaging can be done in difficult cases, and scintigraphy reflects the disease activity. Treatment is mainly surgical for the primary variety; however, a stage-oriented conservative approach using phosphate binders, phosphate restricted diets and acetazolamide should be considered before the surgical approach is pursued due to the high rate of recurrences and complications after surgical intervention. Medical treatment is the mainstay for treatment of the secondary variety, with failure warranting subtotal or total parathyroidectomy. Surgical intervention in these patients should be kept as a last resort.

Tumoral calcinosis: a dental literature review and case report

Tumoral calcinosis (TC) is a rare familial disease characterized by abnormal peri-articular calcification in affected joints, without any associated renal, metabolic or collagen vascular disease. It is characterized by usual hyperphosphataemia with normal serum calcium and alkaline phosphatase values. There are only a few reported cases ofTC patients with dental findings. This article reviews the dental literature and describes progressive gingival, alveolar and mandibular tori enlargement in a 41-year-old female from Zimbabwe with tumoral calcinosis.

CLINICAL RELEVANCE

Tumoral calcinosis is a rare disorder of mineral metabolism with oral manifestations.

FGF23 and syndromes of abnormal renal phosphate handling

Fibroblast growth factor 23 (FGF23) is part of a previously unrecognized hormonal bone-parathyroid-kidney axis, which is modulated by 1,25(OH)(2)-vitamin D (1,25(OH)(2)D), dietary and circulating phosphate and possibly PTH. FGF23 was discovered as the humoral factor in tumors that causes hypophosphatemia and osteomalacia and through the identification of a mutant form of FGF23 that leads to autosomal dominant hypophosphatemic rickets (ADHR), a rare genetic disorder. FGF23 appears to be mainly secreted by osteocytes where its expression is up-regulated by 1,25(OH)(2)D and probably by increased serum phosphate levels. Its synthesis and secretion is reduced through yet unknown mechanisms that involve the phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX), dentin matrix protein 1 (DMP1) and ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Consequently, loss-of-function mutations in these genes underlie hypophosphatemic disorders that are either X-linked or autosomal recessive. Impaired O-glycosylation of FGF23 due to the lack of UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyl-transferase 3 (GALNT3) or due to certain homozygous FGF23 mutations results in reduced secretion of intact FGF23 and leads to familial hyperphosphatemic tumoral calcinosis. FGF23 acts through FGF-receptors and the coreceptor Klotho to reduce 1,25(OH)(2)D synthesis in the kidney and probably the synthesis of parathyroid hormone (PTH) by the parathyroid glands. It furthermore synergizes with PTH to increase renal phosphate excretion by reducing expression of the sodium-phosphate cotransporters NaPi-IIa and NaPi-IIc in the proximal tubules. Loss-of-function mutations in these two transporters lead to autosomal recessive Fanconi syndrome or to hereditary hypophosphatemic rickets with hypercalciuria, respectively.

Miscellaneous non-inflammatory musculoskeletal conditions. Hyperphosphatemic familial tumoral calcinosis (FGF23, GALNT3 and αKlotho)

Familial tumoral calcinosis (TC) is a rare disorder distinguished by the development of ectopic and vascular calcified masses that occur in settings of hyperphosphatemia (hFTC) and normophosphatemia (nFTC). Serum phosphorus concentrations are relatively tightly controlled by interconnected endocrine activity at the level of the intestine, kidney, and skeleton. Discovering the molecular causes for heritable forms of hFTC has shed new light on the regulation of serum phosphate balance. This review will focus upon the genetic basis and clinical approaches for hFTC, due to genes that are related to the phosphaturic hormone fibroblast growth factor-23 (FGF23). These include FGF23 itself, an FGF23-glycosylating enzyme (GALNT3), and the FGF23 co-receptor α-Klotho (αKL). Our understanding of the molecular basis of hFTC will, in the short term, aid in understanding normal phosphate balance, and in the future, provide potential insight into the design of novel therapeutic strategies for both rare and common disorders of phosphate metabolism.

Tumoral calcinosis: a case report

An 11-year-old girl presented with a progressive swelling of the right elbow after a contusion. Radiography and magnetic resonance imaging showed a densely calcified lesion with no periosteal reaction or fracture. The underlying bone and muscles had normal signal intensity. A bone scan revealed increased uptake over the right elbow and the left buttock and acetabulum. Blood tests revealed no abnormality. As the mass progressively increased in size and malignancy could not be excluded, excision was performed 4 months after presentation. A lobulated, yellowish mass with a pseudo-capsule measuring 9x7x4 cm was excised. It was not attached to surrounding muscles, and some chalky, well-defined material emerged from the surface. Histological findings confirmed the diagnosis of tumoral calcinosis. The mass was transversed by fibrous septa with fibroblastic proliferation. Foreign body giant cells and histiocytic cells were found within the septa. There was no evidence of malignancy. Four months later, excision of the left elbow and buttock lesions was performed, and histology of both revealed the same diagnosis. At the 4-year follow-up, there was no recurrence.

Disorders of phosphate homeostasis and tissue mineralisation

Phosphate is absorbed from the diet in the gut, stored as hydroxyapatite in the skeleton, and excreted with the urine. The balance between these compartments determines the circulating phosphate concentration. Fibroblast growth factor 23 (FGF23) has recently been discovered and is part of a previously unrecognised hormonal bone-kidney axis. Phosphate-regulating gene with homologies to endopeptidases on the X chromosome, and dentin matrix protein 1 regulate the expression of FGF23 in osteocytes, which then is O-glycosylated by UDP-N-acetyl-alpha-D-galactosamine: polypeptide N-acetylgalactosaminyl-transferase 3 and secreted into the circulation. FGF23 binds with high affinity to fibroblast growth factor receptor 1c in the presence of its co-receptor Klotho. It inhibits, either directly or indirectly, reabsorption of phosphate and the synthesis of 1,25-dihydroxy-vitamin-D by the renal proximal tubule and the secretion of parathyroid hormone by the parathyroid glands. Acquired or inborn errors affecting this newly discovered hormonal system can lead to abnormal phosphate homeostasis and/or tissue mineralisation. This chapter will provide an update on the current knowledge of the pathophysiology, the clinical presentation, diagnostic evaluation and therapy of the disorders of phosphate homeostasis and tissue mineralisation.

Tumoral calcinosis: a case report

Tumoral Calcinosis is a distinct clinical and histological entity that is characterized by large periarticular deposits of calcium resembling a neoplasm and is found foremost in the region of hip, shoulder and elbow. We report a case of Tumoral Calcinosis in a 25-year-old male who presented to us with gradually increasing swelling of right axilla, and both hips of nearly two years duration. It was diagnostic enigma for the treating surgeons but with the help of an astute pathologist we diagnosed this rare condition and successfully treated it surgically.

Hyperostosis with hyperphosphatemia and tumoral calcinosis: a case report

The combination of hyperostosis and hyperphosphatemia is very rare. In this case report, we present a boy with a combination of diffuse hyperostosis and hyperphosphatemia. We evaluated most possible known causes of hyperphosphatemia and hyperostosis. He had normal renal function and serum parathormone level. Concerning some few similar cases, most of them from Middle Eastern countries, we present this combination (diffuse hyperostosis and hyperphosphatemia) as a new syndrome to be discussed in pediatric textbooks.

Disorders of Tumoral Calcification of the Spine

Tumoral calcium pyrophosphate dihydrate crystal deposition disease and tumoral calcinosis (TC) are rare non-neoplastic conditions which may cause symptoms of spinal cord compression when they manifest in the perispinal tissues. There is little information available to compare these conditions with each other. We report a case of a patient with such a calcified mass impinging on the spinal cord. A 39-year-old woman on hemodialysis presents with progressive quadriparesis and monoplegia and is found to have a large calcified mass impinging on the spinal cord at the level of C3-4. The mass is excised by an anterior approach with corpectomy and fusion. Pathology was tumoral calcium pyrophosphate dihydrate crystal deposition disease versus TC. Both conditions are very rare in the perispinal tissues with 21 reported cases of tumoral calcium pyrophosphate dihydrate deposition disease and 39 cases of TC. Both cause compressive symptoms depending on the site of occurrence. Tumoral calcium pyrophosphate deposition disease is characterized by smaller, round, masses typically in ligamentous structures which may erode into adjacent bone. Tumoral calcinosis displays larger, lobulated, irregular lesions which do not erode into bone. Either lesion may contain calcium pyrophosphate dihydrate or hydroxyapatite. Treatment is surgical decompression, though lesions may recur.

The role of mutant UDP-N-acetyl-alpha-D-galactosamine-polypeptide N-acetylgalactosaminyltransferase 3 in regulating serum intact fibroblast growth factor 23 and matrix extracellular phosphoglycoprotein in heritable tumoral calcinosis

CONTEXT

Familial tumoral calcinosis (TC) results from disruptions in phosphate metabolism and is characterized by high serum phosphate with normal or elevated 1,25 dihydroxyvitamin vitamin D concentrations and ectopic and vascular calcifications. Recessive loss-of-function mutations in UDP-N-acetyl-alpha-D-galactosamine-polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3) and fibroblast growth factor-23 (FGF23) result in TC.

OBJECTIVE

The objective of the study was to determine the relationship between GALNT3 and FGF23 in familial TC.

DESIGN, SETTING, AND PATIENTS

We assessed the major biochemical defects and potential genes involved in patients with TC.

INTERVENTION

Combination therapy consisted of the phosphate binder Sevelamer and the carbonic anhydrase inhibitor acetazolamide.

RESULTS

We report a patient homozygous for a GALNT3 exon 1 deletion, which is predicted to truncate the encoded protein. This patient had high serum FGF23 concentrations when assessed with a C-terminal FGF23 ELISA but low-normal FGF23 levels when tested with an ELISA for intact FGF23 concentrations. Matrix extracellular phosphoglycoprotein has been identified as a possible regulator of phosphate homeostasis. Serum matrix extracellular phosphoglycoprotein levels, however, were normal in the family with GALNT3-TC and a kindred with TC carrying the FGF23 S71G mutation. The tumoral masses of the patient with GALNT3-TC completely resolved after combination therapy.

CONCLUSIONS

Our findings demonstrate that GALNT3 inactivation in patients with TC leads to inadequate production of biologically active FGF23 as the most likely cause of the hyperphosphatemic phenotype. Furthermore, combination therapy may be effective for reducing the tumoral burden associated with familial TC.

Tumoral calcinosis: pearls, polemics, and alternative possibilities

Massive periarticular calcinosis of the soft tissues is a unique but not rare radiographic finding. On the contrary, tumoral calcinosis is a rare familial disease. Unfortunately, the term tumoral calcinosis has been liberally and imprecisely used to describe any massive collection of periarticular calcification, although this term actually refers to a hereditary condition associated with massive periarticular calcification. The inconsistent use of this term has created confusion throughout the literature. More important, if the radiologist is unfamiliar with tumoral calcinosis or disease processes that mimic this condition, then diagnosis could be impeded, treatment could be delayed, and undue alarm could be raised, possibly leading to unwarranted surgical procedures. The soft-tissue lesions of tumoral calcinosis are typically lobulated, well-demarcated calcifications that are most often distributed along the extensor surfaces of large joints. There are many conditions with similar appearances, including the calcinosis of chronic renal failure, calcinosis universalis, calcinosis circumscripta, calcific tendonitis, synovial osteochondromatosis, synovial sarcoma, osteosarcoma, myositis ossificans, tophaceous gout, and calcific myonecrosis. The radiologist plays a critical role in avoiding unnecessary invasive procedures and in guiding the selection of appropriate tests that can result in a conclusive diagnosis of tumoral calcinosis.

Tumoral calcinosis with hyperphosphatemia

Tumoral calcinosis is a rare disorder of mineral metabolism among adolescents and young adults characterized by deposition of calcific masses around large joints. It is less commonly reported in pediatric population and commonly mistaken for bone tumors. Typical lab parameters include hyperphosphatemia with normal levels of serum calcium, parathyroid hormone (PTH) and alkaline phosphatase. A ten-year-old boy with typical features of tumoral calcinosis is presented.

An FGF23 missense mutation causes familial tumoral calcinosis with hyperphosphatemia

Familial tumoral calcinosis (FTC) is an autosomal recessive disorder characterized by ectopic calcifications and elevated serum phosphate levels. Recently, mutations in the GALNT3 gene have been described to cause FTC. The FTC phenotype is regarded as the metabolic mirror image of hypophosphatemic conditions, where causal mutations are known in genes FGF23 or PHEX. We investigated an individual with FTC who was negative for GALNT3 mutations. Sequencing revealed a homozygous missense mutation in the FGF23 gene (p.S71G) at an amino acid position which is conserved from fish to man. Wild-type FGF23 is secreted as intact protein and processed N-terminal and C-terminal fragments. Expression of the mutated protein in HEK293 cells showed that only the C-terminal fragment is secreted, whereas the intact protein is retained in the Golgi complex. In addition, determination of circulating FGF23 in the affected individual showed a marked increase in the C-terminal fragment. These results suggest that the FGF23 function is decreased by absent or extremely reduced secretion of intact FGF23. We conclude that FGF23 mutations in hypophosphatemic rickets and FTC have opposite effects on phosphate homeostasis.

Proposal for a pathogenesis-based classification of tumoral calcinosis

BACKGROUND

Deposition of calcium in skin is currently categorized into a group of disorders referred to as calcinosis cutis. Divisions between types and subtypes within this confusing classification are predominantly based on morphologic differences in the calcification and serve to obscure pathogenesis. This is especially evident in a subtype of calcinosis cutis, known as tumoral calcinosis. Calcifications in cases of tumoral calcinosis share the following characteristics, but without evidence of a common pathogenesis: large size, juxtaarticular location, progressive enlargement over time, a tendency to recur after surgical removal, and an ability to encase adjacent normal structures. The goal of this study was to formulate a pathogenesis-based classification for cases of tumoral calcinosis.

METHODS

In a literature review 121 cases of tumoral calcinosis were identified. These cases, along with a case evaluated in our clinic, were reviewed retrospectively, and their features compared.

RESULTS

Analysis suggests three pathogenetically distinct subtypes of tumoral calcinosis: (1) Primary normophosphatemic tumoral calcinosis: patients have normal serum phosphate, normal serum calcium, and no evidence of disorders previously associated with soft tissue calcification; (2) primary hyperphosphatemic tumoral calcinosis: patents have elevated serum phosphate, normal serum calcium, and no evidence of disorders previously associated with soft tissue calcification; and (3) secondary tumoral calcinosis: patients have a concurrent disease capable of causing soft tissue calcification. Justification for this classification is based on the presence or absence of disorders known to promote soft tissue calcification and statistically significant differences in family history, mean calcification number, mean serum phosphate level, and calcification recurrence after excision.

CONCLUSIONS

A classification for tumoral calcinosis is devised that outlines potential pathogenetic mechanisms and predicts response to therapy and prognosis. Analysis of other forms of calcinosis cutis may reveal definable pathogenetic differences that suggest a coherent classification for all cutaneous calcinoses.

Review of the literature: severe hyperphosphatemia

A patient with a markedly elevated serum phosphorus level (23.9 mg/dL) is described, followed by a brief review of severe hyperphosphatemia. Elevated serum phosphorus levels may be artifactual or true. True hyperphosphatemia is usefully subdivided according to (a) whether phosphorus is added to the extracellular fluid from a variety of exogenous or endogenous sources, or (b) whether the urinary excretion of phosphorus is reduced from either decreased glomerular filtration or increased tubular reabsorption. Severe hyperphosphatemia, defined herein as levels of 14 mg/dL or higher, is almost invariably multifactorial--usually resulting from addition of phosphorus to the extracellular fluid together with decreased phosphorus excretion. The hyperphosphatemia of the patient described herein appeared to result from a combination of dietary phosphorus supplementation, acute renal failure, acute pancreatitis, and ischemic bowel disease, complicated by lactic acidosis.

Tumoral calcinosis revisited--common and uncommon features. Report of ten cases and review

Familial cutaneous and subcutaneous tumoral calcifications are a recognized entity of unknown pathogenesis. The course of calcinosis and various treatments are discussed and the literature concerning the aetiology is reviewed. Our ten cases provided some experience in dealing with tumoral calcinosis and demonstrated, in addition, some clinical phenomena unrecognized previously, such as involvement of the mucous membranes and an erythematous rash preceding the development of calcified nodules.

Tumoral calcinosis in the neck

Tumoral calcinosis manifests soft-tissue calcification, usually near major joints. It variably includes hyperphosphatemia, elevated 1,25-dihydroxycalciferol, and an affected sibling. Serum calcium, alkaline phosphatase, and parathyroid hormone are normal. Tumoral calcinosis of the head and neck is very rare, but this diagnosis should be considered when x-ray film of a poorly defined mass shows irregular soft-tissue calcification.

Tumoral calcinosis

Tumoral calcinosis is an uncommon, usually solitary, tumour-like mass characterized by soft tissue calcification for no apparent reason. Nearly all cases have occurred in negroes, including 2 previously recorded in this country. We report 7 cases seen over a period of 3 years in English caucasian patients and suggest that the condition is not rare but goes unrecognized under a variety of guises. Three of these 7 patients, 2 of whom were on haemodialysis for renal failure, had isolated hyperphosphataemia, which is the only aetiological factor detected so far. Surgical excision appears to be the only effective treatment.

Tumoral calcinosis: case report and review

A case of tumoral calcinosis is presented. The characteristic clinical, radiologic, and pathologic features of this uncommon disease are described and the various speculations about its etiology are examined, based on a review of the approximately 150 cases which comprise the world literature concerning this disease. The differential diagnosis of periarticular calcified soft tissue masses is discussed.

The syndrome of hyperostosis and hyperphosphatemia

Six children, five girls and one boy, presented with recurrent episodes of swelling, pain, and tenderness of the long bones. On roentgenographic examination all had cortical hyperostosis of the affected areas. Serum phosphate concentration was persistently elevated, and calcium values were normal. Bone biopsy and histologic examination in three patients revealed periosteal new bone formation. The Ellsworth-Howard test was performed on three patients; all had a normal phosphaturic response and an increase in urinary c'AMP to exogenous PTH. The EDTA test, performed on one patient, demonstrated significant phosphaturic response, but a minimal drop in serum phosphate concentration. These findings suggest that the association of cortical hyperostosis and hyperphosphatemia is a distinct clinical entity, and that hyperphosphatemia results from decreased renal excretion of phosphate.