Flash, a 5 month old male intact German Shepherd, was presented for evaluation of “bumps felt while the owners were petting him.” He has been healthy and up to date on vaccinations with no other medical history. On physical exam, he was bright, alert, and responsive with no abnormalities on thoracic auscultation or abdominal palpation. On orthopedic exam, he was strongly ambulatory in all limbs with no evidence of joint or long bone pain. There were small, firm, non-painful masses on deep palpation of the caudal cervical region.
Radiographs (Fig. 1) of the region revealed two ovoid soft tissue masses with stippled mineralization arising in the soft tissues lateral and ventral to the cervical vertebral column at the level of C4 and C5. There was no obvious communication, lysis, or periosteal reaction of the surfaces of the C4 and C5 vertebrae. Based off of the radiographic appearance, main differential diagnoses included calcinosis circumscripta, dystrophic mineralization from prior traumatic hematomas, parasitic or foreign body granulomas, cartilaginous exostosis, or neoplasia such as extraskeletal or parosteal chondrosarcoma/osteosarcoma.
Fine needle aspiration (Fig. 2) of these structures showed grossly white fluid material. Brief cytological exam revealed variably sized aggregates of amorphous to granular, lightly to darkly basophilic material. CBC/Chemistry profile was within normal limits. Tru-cut biopsies were performed. Histologically (Fig. 3), multifocal to coalescing lakes of granular mineral were surrounded by a rim of multinucleated giant cells, epithelioid macrophages, and moderate numbers of plasma cells, neutrophils, and lymphocytes. These lakes were separated by fibrous bands containing spicules and trabeculae of woven bone. The findings were consistent with calcinosis circumscripta.
Calcinosis circumscripta is an uncommon syndrome of solitary or multiple masses of ectopic mineralization characterized by deposition of calcium salts in soft tissues. These calcium salts consist primarily of hydroxyapatite crystals or amorphous calcium phosphate. Other names that have been used to describe this syndrome include tumoral calcinosis, calcinosis cutis, calcium gout, lipocalcinosis, tumoral lipocalcinosis, canine gout, apocrine cystic calcinosis, hip stone, granulomatosis and kalkgicht have been used to describe this syndrome.
Lesions have been described to occur within sites of previous trauma, pressure points, peri-articular soft tissues, subcutaneous tissues such as thoracic wall, under the tongue, base of the pinna, on the cheek of Boxers and Boston terriers, paravertebral locations, or rarely in the intestines. One study described the most common location of lesions affecting subcutaneous tissues of the hind limbs (50%), followed by the tongue (23%), and transverse process of C2-C3 (2.6%).
Various species have been reported to be affected including humans, dogs, cats, horses, cows, monkeys, buffalo, rabbits, and a captive sitatunga. In dogs, young, large-breed dogs, particularly those < 2 years of age, with no sex predilection are primarily affected. German Shepherds, Labrador Retrievers, and Rottweilers are overrepresented.
Mineralization of soft tissues has been classified into three types according to underlying factors: metastatic, dystrophic, or idiopathic calcinosis. Metastatic mineralization occurs mostly in man, with derangements in calcium and/or phosphate metabolism and is generally associated with hypercalcemia and/or hyperphosphatemia. Dystrophic mineralization occurs with normal serum calcium and phosphate levels and the calcification is localized to a specific area of tissue injury, necrosis, inflammation, or neoplasia. In animals, the dystrophic form is the most common. Idiopathic mineralization occurs in the absence of known tissue injury, or systemic metabolic defect. No causative factor is identifiable. Breed and familial predilection can occur, specifically in human beings, calcinosis circumscripta can be inherited as an autosomal recessive trait. In dogs, hereditary predilection has been suggested by the occasional occurrence in related dogs.
Treatment consists of surgical removal of affected tissues and is usually curative with excellent prognosis. Rare recurrence may occur. Although the radiographic presence of a nodular, stippled, mineralized mass are highly suspicious of calcinosis circumscripta, histologic evaluation is required to ultimately diagnose this condition.
References available upon request.
Dr. Matthew Paek, originally from the Philadelphia, PA area, graduated from Johns Hopkins University, receiving both bachelors and masters degrees. He then went on to earn his VMD degree from the University of Pennsylvania School of Veterinary Medicine in 2010. After completing a 1-year rotating internship in medicine and surgery at a large private practice in New Jersey, he returned to the University of Pennsylvania for a three-year residency and completed his board certification as a Diplomate of the American College of Veterinary Radiology.
Dr. Paek enjoys all aspects of diagnostic imaging including radiology, contrast studies, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). His clinical areas of interest are advanced imaging of musculoskeletal injuries, central nervous system disorders, and oncological conditions. He has authored scientific articles and has presented at a national American College of Veterinary Radiology conference.
In his spare time, Dr. Paek enjoys spending time with his family including wife, newborn, and Yorkshire Terrier, as well as traveling, and watching Philadelphia sports teams.
Dr. Paek is available for consultations and diagnostics at Hope Advanced Veterinary Center – Rockville
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