Ultrastructural study of the long-term development of two experimental cutaneous calcinoses (topical calciphylaxis and topical calcergy) in the rat

Late-onset subcutaneous scalp calcifications in a patient with pseudo-pseudohypoparathyroidism

Ectopic calcifications and even bone formation have been linked to GNAS gene mutations. A 51-year-old Caucasian female had been diagnosed of pseudo-pseudohypoparathyroidism (PPHP) in 1989. She has always had normal serum parathyroid hormone, calcium, and phosphorus levels. A non-contrast computed tomography of the head was done in 2013 and it showed finely speckled subcutaneous calcifications in the high convexity of the head. Cutaneous exploration did not show any abnormality. We herein report an unusual case of late-onset scalp calcifications in a patient with PPHP.

Three cases of osteoma cutis occurring in infancy. A brief overview of osteoma cutis and its association with pseudo-pseudohypoparathyroidism

We report three cases of primary osteoma cutis in children, two of whom (siblings) were associated with Albright's hereditary osteodystrophy (AHO), manifesting as short stature with autosomal dominant inheritance from the father, but no dysmorphic features and no parathyroid hormone (PTH) resistance. Osteoma cutis can manifest as an isolated skin disease, a secondary condition to other skin diseases (such as acne), or in association with several syndromes, including AHO, which in turn may be associated with PTH resistance. The management and prognosis of patients diagnosed with osteoma cutis is determined by whether the skin manifestation has occurred in isolation, in association with a syndrome, or as a secondary skin disease. These three paediatric cases highlight the importance of understanding the aetiology and associations of osteoma cutis in order to appropriately investigate and manage patients who present with this rare skin disease.

Calciphylaxis in a patient without renal failure or elevated parathyroid hormone: possible aetiological role of chemotherapy

Calciphylaxis is a rare, often fatal disease characterized clinically by progressive cutaneous necrosis and ulceration, and histologically by vascular calcification and thrombosis. It has been described in association with end-stage renal disease, after initiation of dialysis, following renal transplantation, and in patients with hyperparathyroidism. We present the first case of calciphylaxis occurring in a patient with both normal renal function and parathyroid hormone level and discuss the possible aetiological role of chemotherapy-induced functional protein C and protein S deficiency.

The strength of a calcified tissue depends in part on the molecular structure and organization of its constituent mineral crystals in their organic matrix

High-voltage electron-microscopic tomographic (3D) studies of the ultrastructural interaction between mineral and organic matrix in a variety of calcified tissues reveal different crystal structural and organizational features in association with their respective organic matrices. In brittle or weak pathologic or ectopic calcifications, including examples of osteogenesis imperfecta, calciphylaxis, calcergy, and dermatomyositis, hydroxyapatite crystals occur in various sizes and shapes and are oriented and aligned with respect to collagen in a manner which is distinct from that found in normal calcified tissues. A model of collagen-mineral interaction is proposed which may account for the observed crystal structures and organization. The results indicate that the ultimate strength, support, and other mechanical properties provided by a calcified tissue are dependent in part upon the molecular structure and arrangement of its constituent mineral crystals within their organic matrix.

Tomographic imaging of collagen-mineral interaction: implications for osteogenesis imperfecta

The novel method of high voltage electron microscopic tomography (3D) has been applied for the first time to examine ultrastructural features and spatial relations between collagen fibrils and mineral crystals in a mouse mutant (oim/oim) which replicates a moderate to severe form of osteogenesis imperfecta. The animal produces collagen consisting of the alpha1(I) homotrimer and has a brittle calcified skeleton. Three-dimensional image reconstructions of the Achilles tendons, which were found to mineralize in the mutant mice, revealed that their composite crystals were different in their structural appearance and spatial association with collagen compared to that determined in normal calcified tissues. These results indicate that the nature of the organic matrix of a mineralizing tissue critically influences the formation, structure, and location of the constituent mineral and, further, the data are interpreted as suggesting that the unusual structural and organizational interaction between mineral and collagen underlies the inherent brittleness and weakness of calcification in this model of osteogenesis imperfecta.

Microliths in normal salivary glands of cat investigated by light and electron microscopy

This investigation concerns the natural history of microlith in the salivary glands of cat. Microliths were detected in more sublingual than submandibular glands and were almost absent in the parotid. They were found intraparenchymally, intraluminally and interstitially, and ultrastructurally in phagosomes of acinar, ductal and myoepithelial cells, intermixed with the cytoplasm of degenerate acinar cells, and in intraparenchymal macrophages and a multinuclear giant cell. They appear to form in healthy acinar cells during autophagocytosis, and possibly to be discharged luminally, laterally or basally, and to form in the debris of degenerate cells intraparenchymally and intraluminally. They appear to be removed by expulsion in the saliva, scavenging macrophages, and possible eventual degradation in the parenchymal phagosomes. The greater occurrence of microliths in the sublingual gland may relate to a low level of secretory activity, and the near absence of microliths in the parotid to a low level of calcium. The feline salivary glands were found to be an outstanding model for the investigation of microlithiasis.

Osseointegration of metallic implants. II. Transmission electron microscopy in the rabbit

In a material of 10 osseointegrated implants of pure titanium, Tivanium, Vitallium, and stainless steel, 23 interface areas were studied by transmission electron microscopy. The implant site was the upper tibia of mature rabbits, and the observation time was 11 months. The absence of a cellular reaction was verified. However, even in cases of apparently uniform osseointegration, electron microscopy revealed an unpredictable variation in interface ultrastructure within 500-1,000 nm of the metal surface, common to all the materials. There was no structural feature that was specific for a particular material.

Osteoarthrosis and apatite synovitis. Pathological study of a metacarpophalangeal joint

A case of metacarpophalangeal osteoarthrosis associated with synovial apatite deposits is reported. The size of the crystals indicates that they have been thickened by a recrystallization process; the latter could have been provoked by Ca and Po4 ions released by dissolution of some apatite crystals brought by calcified debris of bone or cartilage coming from the abraded osteoarthrotic surfaces. The role of such thickened crystals in synovial inflammation is discussed as well as their possible diagnostic value in determining origin and pathogenesis of a given synovial apatite deposit.