Clinical and genetic analysis of idiopathic normophosphatemic tumoral calcinosis in 19 patients

PURPOSE

Tumoral calcinosis is a rare clinicopathological entity characterized by ectopic soft-tissue calcification, typically periarticular. Normophosphatemic tumoral calcinosis is seldom reported in East Asian populations, and the preoperative diagnosis is often elusive. This study was performed to characterize the clinical profile of normophosphatemic tumoral calcinosis and investigate the presence of the SAMD9 gene mutation.

METHODS

The clinical features, pathological examination findings, and outcomes of 19 subjects were retrospectively reviewed. All patients were analyzed for SAMD9 gene mutation using paraffin-embedded tumoral calcinosis specimens.

RESULTS

Nineteen subjects were analyzed (7 males, 12 females). Their mean age at surgery, mean age at symptom onset, and median disease duration was 51.9 ± 17.3 (range 7-75) years, 49.1 ± 17.2 (range 7-74) years, and 1.3 (interquartile range 0.5-3.0) years, respectively. Lesions were located in the hand in 8 (42.1%) subjects; wrist in 5 (26.3%); shoulder in 2 (10.5%); and hip, knee, buttock, and scrotum in 1 (5.3%) subject each. The lesions in 17 (89.5%) subjects were located around the joints [small joints (hand and wrist) in 13 (68.4%) and large joints (shoulder, hip, and knee) in 4 (21.1%)]. Lesions occurred in the upper limbs in 15 (78.9%) subjects and in the lower limbs in 2 (10.5%). Multiple-lesion involvement (distal right index finger and middle finger) occurred in one (5.3%) subject. Symptoms included pain in 15 (78.9%) subjects, impaired mobility in 5 (26.3%), swelling in 5 (26.3%), numbness in 2 (10.5%), and an asymptomatic mass in 2 (10.5%). The serum inorganic phosphorus concentration was normal in all 19 subjects (mean 1.17 ± 0.15 mmol/L). The serum calcium concentration was normal in 18 subjects and low in 1. The serum alkaline phosphatase concentration was normal in all 19 subjects. Pathological examination indicated multiple nodules of calcified materials that manifested an amorphous or granular blue-purple crystal and were surrounded by proliferation of mononuclear or multinuclear macrophages, osteoclastic-like giant cells, fibroblasts, and chronic inflammatory cells. Notably, different phases of pathological manifestations were observed in the same microscopic field. During follow-up (0.5-65.0 months), no recurrence of tumoral calcinosis was observed in 18 (94.7%) subjects, but 1 subject developed in situ recurrence of an asymptomatic subcutaneous mass after 6 months postoperatively. Genetic analysis in all 19 subjects revealed no SAMD9 gene mutations.

CONCLUSIONS

Most subjects were females and developed calcinosis in adulthood. Small joints (hand and wrist) and the upper limbs were frequently involved. The presence of different phases of pathological features in the same subject suggests that about half of the study participants had been misdiagnosed with another condition (such as gout, osteoarthritis, etc.). Complete surgical excision led to cure without recurrence during follow-up in majority of the study participants.

[β-catenin nuclear translocation represses thyroid cancer stem cells differentiating into cells with sodium-iodine symporter functional expression]

Objective: To confirm whether β-catenin nuclear translocation in thyroid cancer stem cells can differentiate into thyroid cancer cells without functional membrane expression of sodium-iodine transporter (NIS) and be resistant to iodide 131 treatment. Methods: Thyroid cancer stem cells were firstly isolated as a side population (SP) from human thyroid cancer cell line FTC133. The SP cells from FTC133 were transfected with β-catenin, and then differentiated. The cells were further collected for Western blot, Transwell and MTT assay to investigate the epithelial-mesenchymal transition (EMT) characteristics, tumor growth, invasion, and iodine uptake potency in vitro. Functional NIS expression and iodide uptake in differentiated cells were detected with immunofluorescent staining and iodide uptake assay, respectively. Subcutaneous severe combined immunodeficient (SCID) mice tumor model was induced with differentiated cancer cells to explore the in vivo effect of radioiodine treatment. Further immunohistochemical staining was performed to reveal the changes of functional proteins involved in tumor radioiodine treatment. Results: Side population was isolated from FTC133 accounting for about 0.03%, with high expression of stem cell markers and decreased expression of differentiated cell markers. Western blot showed prominent EMT phenotype in the differentiated cells from β-catenin transfected stem cell model, with absence of epithelial expression of E-cadherin and cytokeratin 18, as well as abnormal expression of vimentin,fibronectin and urokinase-type plasminogen activator. Moreover,compared with cells differentiated from untransfected or empty plasmid transfected stem cells, in vitro proliferation markedly increased 85.4% and 81.0%, respectively (both P<0.01); while in vitro invasion augmented 78.8% and 84.4%, respectively (both P<0.01). Immunofluorescent staining identified that, after transfected with β-catenin, differentiated cells underwent β-catenin nuclear translocation and NIS localization transferred from membrane to plasma, compared with cells from untransfected or empty plasmid transfected stem cells. Cell iodide uptake in vitro decreased about 52.8% and 45.2%, respectively (both P<0.01). Furthermore, in vivo experiment further demonstrated that, cells differentiated from β-catenin transfected stem cells were found with much higher tumor proliferation,tumor growth rate and larger tumor mass after radioiodine 131 treatment (both P<0.05). Conclusion: Induction of β-catenin nuclear translocation in stem cells may generate differentiated thyroid cancer cells that are not sensitive to radioiodine treatment.