A case report and review of calcinosis cutis

Commonly associated with autoimmune and renal disorders, calcinosis cutis is a disorder of systemic calcium deposition in soft tissues. The pathophysiology of such deposition varies based on subtype, therefore treatment options vary not only in terms of severity of disease but also with subtype. This case report describes a 52-year-old female with systemic sclerosis and an extensive past medical history who initially presented with complaints of worsening left lower leg pain, a negative workup for deep vein thrombosis, and an extensive palpable mass in the posterior thigh with erythema, drainage, and purulence. With multiple treatment options exhausted from her autoimmune disorders, she ultimately required surgical resection for her refractory infected calcinosis cutis. Identification of calcinosis cutis subtype in conjunction with appropriate history and physical is crucial to determining indications for treatment.

Prevalence and Radiographic Features of Head and Neck Soft Tissue Calcifications on Digital Panoramic Radiographs: A Retrospective Study

Background In this study, we aimed to determine the prevalence and radiographic features of incidental head and neck soft tissue calcifications (STCs) on panoramic imagesand assess their clinical significance. Methodology Following well-established training and calibration procedures, 9,553 digital panoramic radiographs (DPRs) taken between January 1, 2021, and January 31, 22, were retrospectively evaluated. Only obvious calcifications and clear differential diagnoses were considered. The presence, type, side (i.e., unilateral or bilateral), number (single or multiple), and the presence of different calcifications in the same individual were recorded. STCs were recorded according to age and gender. Data were analyzed using the chi-square test and Fisher's exact test using SPSS version 18.0 (IBM Corp., Armonk, NY, USA). Results Overall, 35.8% of the DPRs studied showed the presence of STCs, including ossified stylohyoid complex (OSHC) (10.3%), thyroid cartilage (9.8%), tonsillolith (9.2%), atherosclerotic plaques (5.8%), calcified triticeous cartilage (CTC) (5.1%), sialolith (1.9%), as well as intra-articular (1.3%) and other calcifications (0.1-0.8%), i.e., calcified lymph node, antrolith, rhinolith, phlebolith, and osteoma cutis. STCs were found to be more prevalent in middle-aged patients and in females. A significant relationship was identified between the presence of carotid artery calcification and calcified superior horn of thyroid cartilage (CSHTC), as well as between the presence of CSHTC and CTC. Calcifications were detected either bilaterally (n = 2,003) or unilaterally (n = 2,388); however, OSHC mostly showed bilateral calcifications (8.5%). Conclusions Panoramic radiographs of dental patients reveal the frequent occurrence of STCs in the head and neck region with differing radiographic features. Certain calcifications show gender and age differences. Accurate detection of STCs may guide the identification of potential underlying diseases and help initiate referral to the relevant multidisciplinary teams.

FAM20A mutations and transcriptome analyses of dental pulp tissues of enamel renal syndrome

AIM

Biallelic loss-of-function FAM20A mutations cause amelogenesis imperfecta (AI) type IG, better known as enamel renal syndrome (ERS), characterized by severe enamel hypoplasia, delayed/failed tooth eruption, intrapulpal calcifications, gingival hyperplasia and nephrocalcinosis. FAM20A binds to FAM20C, the Golgi casein kinase (GCK) and potentiates its function to phosphorylate secreted proteins critical for biomineralization. While many FAM20A pathogenic mutations have been reported, the pathogeneses of orodental anomalies in ERS remain to be elucidated. This study aimed to identify disease-causing mutations for patients with ERS phenotypes and to discern the molecular mechanism underlying ERS intrapulpal calcifications.

METHODOLOGY

Phenotypic characterization and whole exome analyses were conducted for 8 families and 2 sporadic cases with hypoplastic AI. A minigene assay was performed to investigate the molecular consequences of a FAM20A splice-site variant. RNA sequencing followed by transcription profiling and gene ontology (GO) analyses were carried out for dental pulp tissues of ERS and the control.

RESULTS

Biallelic FAM20A mutations were demonstrated for each affected individual, including 7 novel pathogenic variants: c.590-5T>A, c.625T>A (p.Cys209Ser), c.771del (p.Gln258Argfs*28), c.832_835delinsTGTCCGACGGTGTCCGACGGTGTC CA (p.Val278Cysfs*29), c.1232G>A (p.Arg411Gln), c.1297A>G (p.Arg433Gly) and c.1351del (p.Gln451Serfs*4). The c.590-5T>A splice-site mutation caused Exon 3 skipping, which resulted in an in-frame deletion of a unique region of the FAM20A protein, p.(Asp197_Ile214delinsVal). Analyses of differentially expressed genes in ERS pulp tissues demonstrated that genes involved in biomineralization, particularly dentinogenesis, were significantly upregulated, such as DSPP, MMP9, MMP20 and WNT10A. Enrichment analyses indicated overrepresentation of gene sets associated with BMP and SMAD signalling pathways. In contrast, GO terms related to inflammation and axon development were underrepresented. Among BMP signalling genes, BMP agonists GDF7, GDF15, BMP3, BMP8A, BMP8B, BMP4 and BMP6 were upregulated, while BMP antagonists GREM1, BMPER and VWC2 showed decreased expression in ERS dental pulp tissues.

CONCLUSIONS

Upregulation of BMP signalling underlies intrapulpal calcifications in ERS. FAM20A plays an essential role in pulp tissue homeostasis and prevention of ectopic mineralization in soft tissues. This critical function probably depends upon MGP (matrix Gla protein), a potent mineralization inhibitor that must be properly phosphorylated by FAM20A-FAM20C kinase complex.

Oral administration of pyrophosphate inhibits connective tissue calcification

Various disorders including pseudoxanthoma elasticum (PXE) and generalized arterial calcification of infancy (GACI), which are caused by inactivating mutations in ABCC6 and ENPP1, respectively, present with extensive tissue calcification due to reduced plasma pyrophosphate (PPi). However, it has always been assumed that the bioavailability of orally administered PPi is negligible. Here, we demonstrate increased PPi concentration in the circulation of humans after oral PPi administration. Furthermore, in mouse models of PXE and GACI, oral PPi provided via drinking water attenuated their ectopic calcification phenotype. Noticeably, provision of drinking water with 0.3 mM PPi to mice heterozygous for inactivating mutations in Enpp1 during pregnancy robustly inhibited ectopic calcification in their Enpp1^−/− offspring. Our work shows that orally administered PPi is readily absorbed in humans and mice and inhibits connective tissue calcification in mouse models of PXE and GACI. PPi, which is recognized as safe by the FDA, therefore not only has great potential as an effective and extremely low‐cost treatment for these currently intractable genetic disorders, but also in other conditions involving connective tissue calcification.

Evolution of gout: "malignant" change over time?

Gout is a common entity; yet it is such a great mimicker in its imaging features that it can confuse clinicians and radiologists alike, sometimes leading to unnecessary investigations and treatment. We present a case of a 52 year old male renal transplant patient who presented with a slow growing mass in his left shin. The initial radiograph demonstrated a non-aggressive looking calcified lesion. A fine needle aspiration demonstrated this lesion to be gout deposition. The lesion was unchanged in the following eight years until the patient reported a sudden growth in size. Imaging showed features of an aggressive lesion with disruption of the previous calcification as well as enhancement on magnetic resonance imaging. Surgical excision biopsy was performed in view of the worrisome features on imaging and the histology showed tophaceous gout. Following description of our case, we reviewed the clinical and imaging features of gout and discussed its differential diagnoses.

ABCC6 is a basolateral plasma membrane protein

RATIONALE

ABCC6 plays a crucial role in ectopic calcification; mutations of the gene cause pseudoxanthoma elasticum and general arterial calcification of infancy. To elucidate the role of ABCC6 in cellular physiology and disease, it is crucial to establish the exact subcellular localization of the native ABCC6 protein.

OBJECTIVE

In a recent article in Circulation Research, ABCC6 was reported to localize to the mitochondria-associated membrane and not the plasma membrane. As the suggested mitochondrial localization is inconsistent with published data and the presumed role of ABCC6, we performed experiments to determine the cellular localization of ABCC6 in its physiological environment.

METHODS AND RESULTS

We performed immunofluorescent labeling of frozen mouse and human liver sections, as well as primary hepatocytes. We used several different antibodies recognizing human and mouse ABCC6. Our results unequivocally show that ABCC6 is in the basolateral membrane of hepatocytes and is not associated with the mitochondria, mitochondria-associated membrane, or the endoplasmic reticulum.

CONCLUSIONS

Our findings support the model that ABCC6 is in the basolateral membrane, mediating the sinusoidal efflux of a metabolite from the hepatocytes to systemic circulation.