Sacroiliac joint involvement in osteochondromatosis: identifying its prevalence and characteristics from cross-sectional imaging

PURPOSE: Apart from a few case reports, sacroiliac joint (SIJ) involvement in osteochondromatosis has not been studied. We aimed to determine the prevalence and characteristics of such involvement using cross-sectional imaging. METHODS: In this retrospective study, three observers (one junior radiologist and two musculoskeletal radiologists) independently reviewed computed tomography (CT) or magnetic resonance imaging (MRI) of patients in our database who had osteochondromatosis (≥2 osteochondromas across the skeleton) for SIJ involvement. The final decision was reached by the consensus of the two musculoskeletal radiologists in a later joint session. RESULTS: Of the 36 patients with osteochondromatosis in our database, 22 (61%) had cross-sectional imaging covering SIJs (14 females, 8 males; age range 7-66 years; mean age 23 years; 13 MRI, 9 CT). Of these, 16 (73%) had intra-articular osteochondromas. For identifying SIJ osteochondromas on cross-sectional imaging, interobserver agreement was substantial [κ = 0.67; 95% confidence interval (CI): 0.34, 1.00] between the musculoskeletal radiologists and moderate (κ = 0.59; 95% CI: 0.23, 0.94) between the junior radiologist and the final consensus decision of the two musculoskeletal radiologists. In the cohort with cross-sectional imaging, the anatomical variations of the accessory SIJ (n = 6, 27%) and iliosacral complex (n = 2, 9%) were identified in six different patients with (n = 2) and without (n = 4) sacroiliac osteochondromas. CONCLUSION: Cross-sectional imaging shows frequent (73%) SIJ involvement in osteochondromatosis, which, although a rare disorder, nevertheless needs to be considered in the differential diagnosis of such SIJ anatomical variants as the accessory SIJ and iliosacral complex. Differentiating these variants from osteochondromas is challenging in patients with osteochondromatosis.

A frameshift variant in the EXT1 gene in a feline leukemia virus-negative cat with osteochondromatosis.

Osteochondromatosis is a benign proliferative disorder characterized by cartilage-capped bony protuberances. In humans and most mammals, variants in the EXT1 or EXT2 gene are strongly correlated with the etiology of osteochondromatosis. However, in cats, osteochondromatosis has only been associated with feline leukemia virus infection. In this study, to explore other factors involved in the etiology of feline osteochondromatosis, we examined the EXT1 and EXT2 genes in a feline leukemia virus-negative cat with osteochondromatosis. Genetic analysis revealed a heterozygous single base pair duplication in exon 6 of the EXT1 gene (XM_023248762.2:c.1468dupC), leading to a premature stop codon in the EXT1 protein. Notably, this frameshift variant is recognized as one of the most common pathogenic variants in human osteochondromatosis. Our data suggest for the first time that genetic variants can have etiologic roles in osteochondromatosis in cats, as in humans and other animals.

A de novo mutation in the EXT2 gene associated with osteochondromatosis in a litter of American Staffordshire Terriers.

BACKGROUND: We aimed to identify mutations associated with osteochondromatosis in a litter of American Staffordshire Terrier puppies. HYPOTHESIS: We hypothesized that the associated mutation would be located in a gene that causes osteochondromatosis in humans. ANIMALS: A litter of 9 American Staffordshire puppies, their sire and dam, 3 of 4 grandparents, 26 healthy unrelated American Staffordshire Terriers, and 154 dogs of 27 different breeds. METHODS: Whole genome sequencing was performed on the proband, and variants were compared against polymorphisms derived from 154 additional dogs across 27 breeds, as well as single nucleotide polymorphism database 146. One variant was selected for follow-up sequencing. Parentage and genetic mosaicism were evaluated across the litter. RESULTS: We found 56,301 genetic variants unique to the proband. Eleven variants were located in or near the gene exostosin 2 (EXT2), which is strongly associated with osteochondromatosis in humans. One heterozygous variant (c.969C > A) is predicted to result in a stop codon in exon 5 of the gene. Sanger sequencing identified the identical mutation in all affected offspring. The mutation was absent in the unaffected offspring, both parents, all available grandparents, and 26 healthy unrelated American Staffordshire Terriers. CONCLUSIONS AND CLINICAL IMPORTANCE: These findings represent the first reported mutation associated with osteochondromatosis in dogs. Because this mutation arose de novo, the identical mutation is unlikely to be the cause of osteochondromatosis in other dogs. However, de novo mutations in EXT2 are common in humans with osteochondromatosis, and by extension, it is possible that dogs with osteochondromatosis could be identified by sequencing the entire EXT2 gene.

[Nora's Lesion: A Rare Differential Diagnosis for Benign Peripheral Bone Tumours]. / Die Nora-Läsion: Eine seltene Differenzialdiagnose bei benignen peripheren Knochentumoren.

We report on a bizarre parosteal osteochondromatous proliferation (BPOP), also known as Nora's lesion, in a 43-year-old female patient.

Feline osteochondromatosis in a FELV-negative European shorthair cat.

OBJECTIVE: To report palliative treatment in a case of multifocal feline osteochondromatosis in a feline leukaemia virus (FeLV) negative European shorthair cat. CASE: A 6-year-old spayed female European shorthair cat was presented because of a right forelimb lameness caused by an osteochondromatous lesion which had trapped tendons, vessels and nerves of the antebrachium. Several other lesions were present which did not cause the animal discomfort. The cat was tested negative for FeLV. Palliative surgical removal of the mass was performed, resulting in a marked improvement of mobility with no local recurrence. The cat developed a non-regenerative anaemia after surgery, however the underlying cause was not identified upon request of the owner. Overall survival after surgery was only 2 months. The cat was then euthanised due to severe progression of the anaemia. CONCLUSION: Palliative surgical removal of osteochondromas may result in local improvement. However, owners need to be aware that it does not increase overall survival and that the prognosis is poor. Infection with FeLV is not necessarily associated with such lesions.

Recurrent bizarre parosteal osteochondromatous proliferation of the ulna with erosion of the adjacent radius: case report.

Bizarre parosteal osteochondromatous proliferation is an unusual entity that should be considered when evaluating a patient with a surface-based bone lesion. The aggressive features of bizarre parosteal osteochondromatous proliferation have occasionally led to misdiagnoses as malignant neoplasms and subsequent aggressive treatment. We present a case of a recurrent forearm bizarre parosteal osteochondromatous proliferation with unique radiographic features. This report serves to illustrate the importance of both radiographic and histopathologic review for correct diagnosis and discusses the successful management of a recurrent forearm lesion.

Neglected synovial osteochondromatosis of the elbow: a rare case.

BACKGROUND: Synovial osteochondromatosis is a benign metaplastic proliferative disorder of the synovium characterised by the formation of multiple cartilaginous nodules in the synovium, many of which detach and become loose bodies. The disease is characteristically monoarticular, most commonly involving the knee. A site in the elbow was first reported in 1918 by Henderson, but any joint may be involved. Very few cases of synovial osteochondromatosis of the elbow have been reported in the literature. The presenting symptoms are usually diffuse discomfort in the affected joint and decreased range of motion with an accompanying gritty or locking sensation. The treatment of choice is excision of the synovium and removal of the loose bodies. CASE PRESENTATION: We report a rare neglected case covering a 32-year period of a locally aggressive synovial osteochondromatosis of the elbow in a 47-year-old man. Clinical examination revealed a significant increase in size of the left elbow compared to the contralateral one. The simple radiographs and the computed tomography showed multiple rounded, calcified bodies widespread throughout the elbow joint. At surgery we removed and counted a total of 312 loose bodies, varying in size from a few millimeters to 3 cm. The evaluation at 6 months postoperatively showed marked reduction in the volume of the elbow, improvement of extension and flexion and an increase of the Mayo elbow performance score from 50 points before surgery to 80 points at 6 months postoperative. CONCLUSION: Synovial osteochondromatosis is an uncommon condition characterized by the formation of multiple nodules of hyaline cartilage within the sub-synovial connective tissue. The differential diagnosis includes chronic articular infection, osteoarthritis, pigmented villonodular synovitis, mono-articular inflammatory arthritis and periarticular neoplasms like synovial sarcoma. The treatment of choice is excision of the synovium and removal of the loose bodies. The prognosis is good, but recurrences may occur if the removal is incomplete.

Occurrence of osteochondromatosis (multiple cartilaginous exostoses) in a domestic pig (Sus scrofa domesticus).

Osteochondromatosis is a condition in which multiple benign, cartilage-capped tumors arise from the surface of bones formed by endochondral ossification. The current report describes the presence of 4 prominent exophytic masses, measuring between 4 and 13 cm in diameter, arising from the surface of the ribs, and located within the thoracic cavity, in a 2-year-old female domestic pig (Sus scrofa domesticus). Histological studies revealed that masses were well-differentiated, cartilage-capped proliferations with an orderly pattern of endochondral mineralization toward deeper areas. The observed gross and microscopic findings are characteristic of osteochondromatosis.

[Relapse of a parosteal osteochondromateous proliferation (Nora's lesion) of the distal thumb]. / Rezidiv einer bizarren paraossären osteochondromatösen Proliferation (Nora-Läsion) des Daumenendgliedes.

We report the case of a 29-year-old female patient with a relapse of a Nora lesion in an atypic location. The literature for this rare benign lesion is reviewed and etiology, diagnostics and therapy are discussed.

Cartilaginous tumours and calcified lesions of the hand: a pictorial review.

Cartilaginous tumours of the extremities are commonly seen in radiographs. Enchondroma is the most frequently encountered tumour. Since the vast majority of enchondromas are asymptomatic, they are typically discovered as incidental findings or along with a pathologic fracture. The authors propose a pictorial review to illustrate the imaging features of cartilaginous bone lesions of the hand and their specificities, and discuss the main differential diagnoses.

[A man with a swelling of the knee]. / Een man met een zwelling in zijn knieholte.

A 72-year-old male presented with a dorsomedial swelling of the knee. X-rays showed isolated ossificated cartilage particles. The particles, which were found to be in a popliteal cyst, were surgically removed and analyzed by the pathologist. The diagnosis was synovial osteochondromatosis . Isolated synovial osteochondromatosis inside a popliteal cyst is uncommon.

High resolution ultrasonography in the diagnosis of ulnar nerve lesions with particular reference to post-traumatic lesions and sites outside the elbow.

OBJECTIVE: Recent studies suggest that high resolution ultrasonography (HRU) is useful in evaluating ulnar neuropathy (UN) at the elbow. These studies do not include UN outside the elbow and lesions related to previous trauma. We investigate diagnostic utility of HRU in UN at any location of traumatic and non-traumatic etiology. METHODS: Patients with clinically suspected and electrophysiologically defined UN at the elbow and outside the elbow were included. Nerve conduction studies (NCS) were compared with HRU. HRU defined UN in terms of change in cross-sectional area. RESULTS: Our retrospective analysis included 46 UN. In 25 cases both NCS and HRU localised neuropathy to the elbow. In 15 where NCS was abnormal but non-localising, HRU localised the lesion in 14, 7 outside the elbow. In three of these, HRU characterised further pathology (synovial osteochondromatosis (n=2), myositis ossificans (n=1). Cross-sectional area of the ulnar nerve at the sulcus significantly correlated with distal NCS parameters. CONCLUSIONS: HRU is of greater use than NCS in the localisation of UN both at the elbow and outside the elbow and in UN related to previous trauma. SIGNIFICANCE: HRU is useful for the localisation of ulnar neuropathy.

[Bizarre parosteal osteochondromatous proliferation or Nora's lesion]. / Prolifération ostéocartilagineuse parostéale bizarre ou lésion de Nora.

Bizarre parosteal osteochondromatous proliferation (BPOP) is a very rare benign lesion on face bones. The first line treatment is surgical exeresis. The frequency of recurrence after exeresis may suggest a malignancy.

Bizarre parosteal osteochondromatous proliferation and periosteal chondroma: a comparative report and review of the literature.

Bizarre parosteal osteochondromatous proliferation and periosteal chondroma are rare, benign, bony lesions that may present in the hand. Bizarre parosteal osteochondromatous proliferation was first reported in the literature by Nora in 1983, and periosteal chondroma was first reported by Lichtenstein in 1952. This report provides a unique side-by-side comparison of these lesions, illustrating each with a clinical vignette. This report, coupled with a thorough review of the literature, serves to demonstrate that the history and physical exam characteristics, as well as the radiographic and gross appearances, are insufficient to differentiate between the two lesions. Histopathologic examination is required to confirm the diagnosis.