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Orthopaedic Hardware, Total Joint Replacements, and Their Complications
Published in Harry Griffiths, Musculoskeletal Radiology, 2008
Pin track infections have a characteristic appearance. Initially, placing a pin in a bone compresses the surrounding bone and usually produces a somewhat sclerotic ring seen end on. If this becomes infected, this sclerotic ring (a sequestrum) becomes surrounded by infected and destroyed bone (an involucum). Once established, this has a characteristic appearance (Fig. 8).
Benign tumors
Published in Archana Singal, Shekhar Neema, Piyush Kumar, Nail Disorders, 2019
Osteoid osteoma occurs in virtually all bones, making up 1%–2% of all hand tumors; 8% of them occur in the phalanges, but localization in the distal phalanx is rare. Most develop in young adults, but there was also one probable congenital case.243 Osteoid osteomas of the nail region cause enlargement of the tip of the digit and nail, clubbing, and nail thickening.244 This unique bone lesion is characterized by marked pain,245 which is nagging to pulsating at night and reacts promptly to non-steroidal anti-inflammatory agents including acetylsalicylic acid. The pain was attributed to the effect on nerves and vessels by prostaglandin E2 produced by the osteoblasts.246 Osteoid osteomas of the distal phalanx present diagnostic difficulties because of their atypical radiological appearance, presence of soft tissue enlargement and nail deformity, the small size of the distal phalanx, and consequent close approximation of lesions to the nail plate and distal interphalangeal joint.247 Subperiosteal localization may mimic an exostosis.248 Probing elicits pain and helps to localize the tumor. Radiography exhibits a small area of contrast rarefaction surrounded by a narrow sclerotic ring.249 Arteriography, thermography, scintigraphy, color-coded duplex US,250 fine-layer computed tomography, and MR imaging help to make the diagnosis and to find the lesion. Preoperative administration of a tetracycline and examination of the lesion under UV light during surgery allows the nidus to be visualized intraoperatively.251 Complete extirpation is the treatment of choice, either by surgery or radiofrequency ablation.
Tumors with adipocyte, myxoid, muscular, osseous, and cartilaginous features
Published in Eckart Haneke, Histopathology of the NailOnychopathology, 2017
Osteoid osteoma is a peculiar bone lesion with a characteristic pattern of pain independent of physical activity.88 Nagging to pulsating pain at night, reacting promptly to nonsteroidal anti-inflammatory agents or acetylsalicylic acid (Aspirin®) is characteristic.89,90 The pain has been attributed to the effect on nerves and vessels by the prostaglandin E2 produced by the osteoblasts.91 They occur in virtually all bones. Approximately 1%–2% of all hand tumors are osteoid osteomas, 8% of them occur in the phalanges, but localization in the distal phalanx is rare.92,93 Most of these tumors develop in young adults, but there was also one probable congenital case.94 Osteoid osteomas of the nail region lead to enlargement of the tip of the digit, clubbing, nail thickening, and enlargement of the nail.95–97 Osteoid osteomas of the distal phalanx often present diagnostic difficulties due to the atypical radiological appearance, the presence of soft tissue enlargement and nail deformity, the small size of the distal phalanx, and consequent close approximation of lesions to the nail plate and distal interphalangeal joint.98,99 Subperiosteal localization may mimic an exostosis.100,101 Probing may elicit pain and help to localize the tumor. Radiography exhibits a small area of contrast rarefaction surrounded by a narrow sclerotic ring.102–104 Arteriography,105 thermography,106 scintigraphy,107 color-coded duplex ultrasonography,108 fine layer computed tomography, and magnetic resonance imaging109 help to make the diagnosis and to find the lesion. Preoperative administration of a tetracycline and examination of the lesion under UV light during surgery allows the nidus to be visualized intraoperatively.110 Treatment is complete extirpation, either by surgery or radiofrequency ablation.111
Development of scleral ossicles in Podocnemis expansa (Testudines: Podocnemididae) embryos exposed to atrazine
Published in Drug and Chemical Toxicology, 2021
Isabela Vieira Carneiro, Lucélia Gonçalves Vieira, Juliana dos Santos Mendonça, Líria Queiroz Luz Hirano, Sady Alexis Chavauty Valdes, Lorena Tannús Menezes-Reis, André Luiz Quagliatto Santos
The sclera, the outermost layer of the eye, is a tough structure that prevents the eyeball from changing shape in response to internal and external pressures. In some animals, scleral ossification may lead to the formation of a sclerotic ring. This structure provides support to the origin of the ciliary muscle of the lens, maintaining eyeball convexity and contributing to lens accommodation via eye shape modification, which in turn leads to changes in the distance between the cornea and fundus (Lawton 2006, Liem et al. 2012). Sclerotic rings, or scleral ossicles, are bony plates found in several vertebrate groups, including Teleosts (Franz-Odendaal 2006), Squamata (Atkins and Franz-Odendaal 2016), Testudines (Warheit et al. 1989, Franz-Odendaal 2006, Vieira et al. 2007), Galliformes (Underwood 1970) and Psittaciformes (Lima et al. 2009).