A 13-year-old Turkish girl presented with a painful firm mass over the left lateral gluteal region, which was surgically excised. The lesion recurred and was excised again at ages 15 and 17 years. When she was 26 years old, the lesion reappeared as a small nodule, which gradually expanded to become a large mass of about 10 cm in diameter (). At the center of the lesion there was a skin erosion of 3×2 cm with an exposed area of gritty whitish material.
Figure 1 Plain radiographs of pelvis (1a) and knee (1b) with calcifications in Patient 1. Radiologic findings in Patient 2: Hyperostosis of the long bones with periosteal appositions and metaphyseal densification in diaphysis (2a); right elbow calcification (2b). (more ...)
She had no other medical conditions. The patient was the fourth of six children born to a known consanguineous marriage. Her grandfathers were first cousins. However, there was no family history of kidney stones, calcifications, or systemic illness. Physical examination revealed a hard, tender, irregular mass of about 10 cm in the left gluteal region (). Tenderness of the left hip abductor muscles limited active abduction, while the passive hip joint mobility was unaffected. She had a palpable hard 7 cm non-tender mass in the right popliteal fossa, with full extension of the knee but with mild limitation in flexion (). Vital signs were normal. There was no lymphadenopathy, and the remainder of the physical examination was within normal limits.
She had hyperphosphatemia (6.2 mg/dl), while serum calcium, uric acid, alkaline phosphatase, creatinine and blood urea nitrogen were within the normal range (). An appropriate sample was not available for measurement of FGF23. Complete blood count showed no abnormality. Skeletal radiographs revealed heterogeneous juxta-articular calcified masses adjacent to the greater trochanter on both hips, in the right popliteal fossa, and on the medial aspect of the right foot, adjacent to the first toe (). Adjacent joints and the contiguous bones were unaffected. The lesions at the right hip, knee and foot were asymptomatic.
Representative laboratory data of the patients.
The patient was hospitalized for the fourth resection of the left hip mass. The excised mass was composed of a whitish gritty material with an incomplete fibrous covering. Histopathological preparation demonstrated calcium deposits surrounded by dense fibrous tissue and occasional histiocytes. Following the operation, the patient did not have any significant complications until the left hip lesion recurred 18 months later.
Genetic analysis of the GALNT3 gene demonstrated a G>A transition in exon 2 (c.485G>A), which resulted in a substitution of arginine 162 to glutamine (p.R162Q) (). The mutation was not found in more than 90 healthy Caucasian samples (data not shown).
Mutational analysis of the GALNT3 gene. Electropherograms of PCR products show wild-type sequences (top) and mutated sequences (bottom) in four patients. Arrows indicate nucleotides involved in the mutations.
A five-year-old girl presented with a six month history of painful left lower leg swelling. Her previous medical history was negative, and her parents were first degree cousins from Sri-Lanka with unremarkable family history. Tibial radiographs demonstrated circumferential endosteal and periosteal bone proliferation with patchy sclerosis of the medullary canal, consistent with hyperostosis (). Multifocal osteomyelitis was considered. Biopsy demonstrated reactive non-specific new bone, fibroblastic stroma infiltrated by lymphocytes and polynuclear cells. Cultures grew Staphylococcus aureus, and antibiotics were administered. After treatment, there was no radiographic change in the tibia, but technetium MDP bone scan demonstrated markedly increased uptake in tibia, femur and forearm.
Nine months later, a painful mass in the left elbow developed and then fifteen months later, a similar mass developed in the right elbow. Radiographs demonstrated peri-articular calcified lesions (). The diagnosis of tumoral calcinosis was considered. Biochemical evaluation revealed elevated serum phosphorus (7.2 mg/dl) (). Other biochemical evaluation included normal serum and urine calcium, alkaline phosphatase, and PTH. Her 25-hydroxyvitamin D [25(OH)D] was low (7 ng/ml) with inappropriately normal 1,25(OH)2D (48 pg/ml). Elevated concentrations of C-terminal FGF23 fragments (563 RU/ml) with concomitant low intact FGF23 (11 pg/ml) were compatible with the diagnosis of tumoral calcinosis.
At the age of 11, she is growing along the 75th centile for height but continues to have 2 or 3 episodes a month with fever, local inflammation, pain and tender swelling over the long bones. Hearing is not impaired, and no dental abnormalities are noted. She had undergone multiple excisions for the massive juxta-articular calcific deposit in the left elbow. To date, her serum phosphate and areas of calcinosis have not responded clinically to attempted treatment with oral sevelamer (a non-calcium phosphate binder) and methotrexate. Family members tested were free of clinical or laboratory abnormalities related to tumoral calcinosis.
Mutational analysis of this patient revealed a homozygous deletion of C in exon 3 of the GALNT3 gene (c.677delC) (). This frame shift mutation is predicted to cause premature termination and produce significantly truncated GALNT3 protein with 277 amino acids (instead of 633 amino acids synthesized from the wild-type allele).
A 15-year-old Lebanese male presented with abnormal gait and hip pain following strenuous sport activity. Radiographs showed femoral epiphysiolysis with severe coxa valga (). There was no known history for consanguinity. Screening for lysosomal storage disease was negative. Surgical correction of the coxa valga was performed because of the risk for slipped capita femora epiphysis. Three months later, he presented with severe right tibia pain and localized swelling in the distal third of the leg. X-rays revealed periosteal appositions and diaphyseal hyperostosis without distinguishable medullary canal (). No ectopic calcification was demonstrated. Magnetic resonance imaging (MRI) showed inflammatory process and technetium scintigraphy displayed localized increased uptake at the tibia diaphysis. The bone biopsy eliminated osseous malignant processes, showing non-specific fibrous tissue with lymphocytic peri-vascular infiltration of the periosteum. A blood count and serum calcium were normal, but no serum phosphorus measurement was performed during this first hospitalization. His symptoms gradually resolved with analgesics and restriction of physical activities.
Nine months later, following a fishing trip, he developed similar pain in the opposite tibia. Radiographs showed new mild broadening of the left diaphysis, with linear periosteal reaction but without any ectopic calcification (). This left tibial local hyperostosis was not present on the previous radiographs. The original right tibial lesion had normalized (). Hyperphosphatemia (7.9 mg/dl) was detected with inappropriately elevated tubular reabsorption of phosphate (TRP) of 96 %. Other biochemical evaluation included normal serum and urine calcium, alkaline phosphatase, and PTH (). 25(OH)D and 1,25(OH)2D were also normal. The C-terminal FGF23 concentration was elevated (958 RU/ml) with inappropriately normal intact FGF23 (26 pg/ml). Symptoms improved in a few weeks with paracetamol, ibuprofen and leg immobilization using a splint. Two years later, he remains asymptomatic.
The patient was homozygous for a G>A transition in the donor splice site of intron 8 (c.1392+1G>A or IVS8+1G>A) of the GALNT3
gene (). An in silico
analysis of the intronic mutation, using NNSPLICE version 0.9 (http://www.fruitfly.org/seq_tools/splice.html
) predicts complete disruption of the donor splice site, likely resulting in skipping of the adjacent exon 8 or activation of cryptic donor splice site(s).
A Greek woman initially presented at 8 years of age with sudden onset of a painful inflammatory mass in the muscles medial to the upper right tibia, accompanied by a low fever. The symptoms improved with acetylsalicylic acid. One month later she had removal of an approximately 6 cm tibial lesion involving both cortical and trabecular bone. Histologically, the lesion incorporated mature trabeculae, some loose fibroblastic tissue, some areas with increased concentrations of osteoblasts producing osteoid, small collections of inflammatory cells, and cortical bone. Mature cortical bone was noted along with intact periosteum but increased subperiosteal ossification. The pathologic interpretation was one of possible osteoid osteoma. Post-operatively, she was free of symptoms and the right leg bony lesion was not evident on later radiographs (ages 15 and 20).
At age 14 an approximately 5 cm subcutaneous calcified lesion was removed from her external upper right thigh, followed by removal of a smaller (2cm) calcified mass in her left hand (metacarpal region). Histologically nodular masses containing deposits of calcium salts were separated and surrounded by dense fibrous connective tissue with abundant histiocytes and polynuclear giant osteoclasts, consistent with tumoral calcinosis. The only reported biochemical abnormality was hyperphosphatemia.
At age 15 she was referred for evaluation and management of recurrent calcified masses and hyperphosphatemia. She had been otherwise healthy without a history of inflammatory conditions or kidney disorders. The parents originate from two small villages (4 km apart) in Greece, but there is no known consanguinity. Her 14 year old brother was healthy. The patient’s mother had three sisters and one brother. Her second maternal aunt died from unknown causes in infancy. The patient’s father is healthy and has five siblings (two sisters and three brothers). There is no family history of similar calcified masses or mineral disorders.
On examination, she was a healthy, fully developed female of normal height (159 cm) and weight (58 kg). She had scars from previous surgeries. Palpation of the right thigh scar revealed a 1.5 cm hard mass, suggesting a remnant or a recurrence of the previous mass. A 1.5 cm area of vitiligo on her left abdomen was observed. She has all her teeth, but those of the front of the upper jaw were repaired after an injury at the age of 5. Dental radiograph revealed absence of pulp chambers and root canals, and short bulbous roots in almost all teeth with only a few exceptions (). MRI of the head indicated very small calcifications of the basal ganglia.
Laboratory testing at age 15-16 revealed hyperphosphatemia (6.5-6.8 mg/dl), and inappropriately increased 1,25(OH)2D (57 pg/ml), but low 25(OH)D (17 ng/ml) (). She had normal serum calcium (9.5-10.0 mg/dl), magnesium (1.8-1.9 mg/dl), uric acid (4.6 mg/dl) and intact PTH (31-46 ng/ml). Renal TRP was inappropriately elevated (96.3%) in the setting of hyperphosphatemia. Based on the findings of soft tissue calcification, hyperphosphatemia, and inappropriately normal 1.25(OH)2D, the diagnosis of hyperphosphatemic tumoral calcinosis was made. C-terminal FGF23 concentrations were elevated (1066 RU/ml), while intact FGF23 concentration was inappropriately low normal (20 pg/ml).
She was advised to avoid phosphate rich foods, and phosphate binding therapy began with aluminum hydroxide 800 mg three times daily and acetazolamide 250 mg daily. Initially, the patient’s compliance was poor. The mass grew further, and at age 16, three calcified masses (12 × 5, 10 × 5, and 5 × 5 cm) were removed. The histology was identical to the previously removed mass. She developed mild anemia (HCT 36%, serum ferritin 14 ng/ml), and oral ferrous sulfate was prescribed. During the next two years her medication compliance improved, and her serum phosphorus decreased slightly. However, she remained hyperphosphatemic (5.6-6.0 mg/dl) with elevated TRP (87-94%).
At age 19 a trial of oral risedronate 35 mg weekly began with the goal of additional improvement in the biochemical profile. At age 20, risedronate and acetazolamide were discontinued, and the dose of aluminum hydroxide was reduced. Addition of probenecid for eight months did not change the biochemical profile, except for a small reduction of serum uric acid to 2.8 mg/dl. However, during the last 6 years of treatment there has been no recurrence of calcified masses as demonstrated by skeletal survey radiographs. Recent ophthalmological examination was also negative for angioid streaks of the retina.
Mutational analysis of the GALNT3 gene showed a homozygous mutation in exon 10 (c.1720T>G), which affects amino acid coding (p.C574G) (). The patient’s asymptomatic parents and brother were heterozygous for this nucleotide substitution. This change was not found in the first maternal aunt and 92 healthy white Americans by PCR-RFLP analysis (data not shown).