Bone marrow lesions, subchondral bone cysts and subchondral bone attrition are associated with histological synovitis in patients with end-stage knee osteoarthritis: a cross-sectional study.

OBJECTIVE: The aim of this study was to examine the osteoarthritis (OA)-related structural changes associated with histological synovitis in end-stage knee OA patients. METHODS: Forty end-stage knee OA patients (female: 88%, mean age: 71.8 y) were enrolled. All participants underwent 3.0-T MRI. The structural changes, such as cartilage morphology, subchondral bone marrow lesion (BML), subchondral bone cyst (SBC), subchondral bone attrition (SBA), osteophytes, meniscal lesion and synovitis, were scored using the whole-organ MRI scoring (WORMS) method. Synovial samples were obtained from five regions of interest (ROIs) of the knee joint during total joint replacement surgery. The associations between the histological synovitis score (HSS) and WORMS or the synovial expression levels of cyclooxygenase (COX)-2, interleukin (IL)-1ß, IL-6 and transforming growth factor (TGF)-ß were examined using Spearman's correlation coefficient. RESULTS: Among the seven OA-related structural changes, the BML, SBC, SBA and synovitis were significantly associated with the HSS (r = 0.33, 0.35, 0.48 and 0.36, respectively), while other morphological changes were not. Although synovial COX-2, IL-1ß or IL-6 expression levels were not associated with the HSS, the synovial TGF-ß expression levels were associated with the HSS. CONCLUSION: The presence of BML, SBC and SBA was associated with histological synovitis in end-stage knee OA patients.

Cementum-like matrix in solitary bone cysts: a unique and characteristic but yet underrecognized feature of promising diagnostic utility.

Solitary bone cysts (SBCs) are benign, intraosseus, cystic lesions, which generally involve metaphysis of long bones during the period of skeletal immaturity. Histologic features are nonspecific, but identification of amorphous cementum-like material provides a significant diagnostic clue. This material is unique to SBC with reported frequency of 10% to 70% and has been described as an immature form of bone. We retrieved and reviewed 41 cases of SBC reported in the last 10 years. The ages of patients ranged from 4 to 64 years (mean, 16 years), with a male-to-female ratio of 3:1. Humerus and femur were the most common sites. Cementum-like matrix was observed in 26 cases (63.4%). This material was seen in different phases of deposition and progression, ultimately transforming into mature bone as seen in 4 cases. Cyst wall lining was observed in 70.7% of cases along with several other nonspecific histologic features including reactive bone formation, hemosiderin macrophages, hemorrhage, multinucleated giant cells, foamy macrophages, fibrin, cholesterol clefts, and granulation tissue. Cementum-like material in the wall of SBCs is a specific and fairly consistent finding of diagnostic significance in cases where cyst wall lining is deficient. We also histologically demonstrate, for the first time, transformation of cementum-like material into reactive and mature bone, which further validates the immature osteoid nature and finding of other authors.

The nature of the characteristic cementum-like matrix deposits in the walls of simple bone cysts.

AIMS: Simple bone cysts (SBC) are benign tumour-like lesions, generally occurring in the metaphyses of long bones before skeletal maturity. Remarkably, in 10-70% of cases, a peculiar, amorphous and hypocellular matrix is found in the walls of SBCs which is usually regarded to consist of (calcified) fibrin clots in the literature. Because these deposits are strongly fuchsinophilic in routine van Gieson stains, the aim of this study was to investigate a series of SBCs using immunohistochemistry and electron microscopy. METHODS AND RESULTS: A comprehensive panel of antibodies against fibrin as well as collageneous and non-collageneous proteins of bone was used, and detected substantial amounts of collagen and decorin as the main components of the investigated matrix. Electron microscopy clearly underlined the immunohistochemical results and also showed abundant fibrils with a periodic banding characteristic of collagen. Adjacent to and in between these collagen deposits runx-2- and osterix-expressing cells were detectable, most probably representing immature osteoprogenitor cells. CONCLUSIONS: Although still stated in the literature and most current textbooks, we were not able to detect any evidence of fibrin as a component of the respective matrix deposits that seem to consist predominantly of collagen and decorin.

The role of molecular diagnostics in aneurysmal and simple bone cysts - a prospective analysis of 19 lesions.

Aneurysmal (ABC) and simple bone cysts (SBC) have been traditionally distinguished by radiological and histopathological features. However, there is some radiological and histopathological overlap between ABC and SBC. ABC is characterised by USP6 fusions while, recently, NFATC2 fusions have been found in a large proportion of SBC. Identifying these fusions may assist in confirming the diagnosis of either ABC or SBC. To elaborate the potential benefit of molecular testing, we report a prospective series of 19 consecutive bone cysts with comprehensive radiological, histopathological and molecular diagnostics. Integrating radiological, histopathological and molecular findings, 11 cysts were diagnosed as SBC and 8 as ABC. Radiologically, 6 of 11 SBC and 6 of 8 ABC were diagnosed as ABC. Fibrin-like collagen deposits were identified in 8 of 11 (73%) SBC and 3 of 8 (38%) ABC. Nodular fasciitis-like areas were identified in 6 of 8 (75%) ABC and in 7 of 11 (64%) SBC. A USP6 fusion was identified in all 8 ABC, including a novel RBM5-USP6 fusion. An NFATC2 fusion was found in 7 of 11 SBC (FUS-NFATC2 fusion in 5 and EWSR1-NFATC2 in 2 cases). There is radiological and histopathological overlap between SBC and ABC in a significant proportion of cases. A diagnosis of ABC is frequently suggested radiologically in SBC, and fibrin-like deposits, thought to be specific for SBC, may be found in some ABC. Molecular testing may significantly improve diagnostic accuracy in bone cysts.

A primary large cholesterol cyst of the mastoid presenting with dysgeusia.

The occurrence of postoperative secondary cholesterol cysts in the mastoid has been previously reported, however the occurrence of a primary large cholesterol cyst in the mastoid with bony destruction of the facial nerve has rarely been reported. The case report of a 17-year-old female patient with a primary large cholesterol cyst with dysgeusia is presented. Computed tomography and magnetic resonance imaging findings for the lesion distinguish a cholesterol granuloma, cholesteatoma and vascular tumor. The patient underwent a canal wall down mastoidectomy with mastoid obliteration. A dehiscent portion of the mastoid segment of the facial nerve was visible within the cavity; the gross finding of the facial nerve was edematous in appearance. Five years later, there has been no recurrence of disease.

Silencing of cytoskeleton-associated protein 2 represses cell proliferation and induces cell cycle arrest and cell apoptosis in osteosarcoma cells.

Osteosarcoma is the most common primary bone malignancy, mainly occurring in children and adolescents. Cytoskeleton-associated protein 2 (CKAP2), which plays important roles in cell proliferation, has been reported to be overexpressed in diverse human cancers. In the present study, we aimed at exploring the expression and functions of CKAP2 in osteosarcoma. The mRNA and protein expression of CKAP2 was analyzed on collected osteosarcoma and control bone cyst tissues. The results indicated that CKAP2 expression was remarkably elevated in osteosarcoma tissues compared with bone cysts tissues. The expression level of CKAP2 in osteosarcoma was associated with overall survival, tumor size and tumor stage. In addition, down-regulation of CKAP2 by RNA interference in osteosarcoma cell lines, MG63 and SW1353, caused a remarkable inhibition in cell proliferation in vitro and xenograft growth in nude mice. Silencing of CKAP2 also significantly induced G0/G1 arrest and cell apoptosis of osteosarcoma cells. Furthermore, phosphorylation levels of Janus kinase 2 (JAK2) and Signal transducers and activators of transcription 3 (STAT3) were significantly reduced in CKAP2 knockdown cells. The expression of downstream targets of JAK2/STAT3 signaling, Cyclin D1, Bcl-2 and survivin, was also decreased in CKAP2 knockdown cells. Such aberrations can be rescued by re-expression of RNAi-resistant CKAP2. Collectively, the present study indicates that CKAP2 is a potential oncogene by targeting JAK2/STAT3 signaling, and that CKAP2 may serve as a novel target for osteosarcoma therapy.

False-Positive 131I Uptake in a Benign Bone Lesion on Post-therapy Scan.

A 56-year-old woman underwent near-total thyroidectomy and papillary thyroid carcinoma without extrathyroidal extension was diagnosed. The serum thyroglobulin (Tg) level was 2.4 µg/L, and anti-Tg was negative when serum thyroid-stimulating hormone level was 85 µIU/mL. She received 100 mCi (3.7 GBq) of 131I. Besides the residual thyroid tissue, a focal uptake in the left clavicular bone was seen on posttherapy 131I images. Then, CT and MRI were performed to diagnosis. All imaging findings suggested that it was a benign bone cyst. At 6-month follow-up, the serum Tg level was undetectable with the thyroid-stimulating hormone level of more than 150 µIU/mL.

Primary intraosseous ganglioneuromatous paraganglioma of the sacrum with immunopositivity for cytokeratin.

BACKGROUND: Paragangliomas are derived from neurosecretory cells believed to be of neural crest origin. A spinal location of paraganglioma is rare and usually presents as an intradural mass. PATIENT AND METHODS: A primary intraosseous paraganglioma of sacrum is extremely unusual, and only 6 cases were reported. In this study, we report a rare case of a 44-year-old man with the complaint of low back pain and lower extremity weakness. Imaging workup, including computerized tomography (CT), and magnetic resonance imaging (MRI) presented an intraosseous sacral lesion with invasion of sacrum in the S1-S3 vertebrae, and extension to L4-L5 spinal canal. The patient underwent subtotal tumor resection, followed by radiation therapy. RESULTS: The morphological and immunohistochemical studies revealed a composite tumor of paraganglioma and ganglioneuroma components, with immunopositivity for cytokeratin. CONCLUSIONS: To the best of our knowledge, this is the first report in the literature demonstrating an intraosseous sacral paraganglioma with these 2 pathological features.

Heterogeneity of presenile dementia with bone cysts (Nasu-Hakola disease): three genetic forms.

Nasu-Hakola disease (NHD) is an autosomal recessive disorder characterized by presenile dementia and bone cysts. Finnish patients revealed a large deletion in DAP12 gene encoding a key element for transducing activation signal. The authors examined six Japanese cases for DAP12 alleles. Five of the six had loss-of-function mutation, either a single-base deletion or a novel point mutation. The single patient without mutation normally expressed DAP12 protein. Japanese NHD has at least three genetic forms regarding DAP12.

Immunocytochemical markers (endothelial and histiocytic) and ultrastructure of primary aneurysmal bone cysts.

Since the first description of an aneurysmal bone cyst in 1942, the pathogenesis of this tumor-like lesion has been controversial. Aspects of interest for elucidating the nature of this lesion include the cellular linings of the aneurysmal cavity systems as well as the character and cellular composition of the stromal septa. To clarify these features, seven aneurysmal bone cysts were studied electron microscopically and immunocytochemically with endothelial (Factor VIII-related antigen, monoclonal endothelial marker) and histiocytic (alpha 1-antitrypsin, alpha 1-antichymotrypsin, lysozyme, acid phosphatase) markers. Both immunocytochemical and electron microscopic examination revealed that the aneurysmal cavernous spaces have no endothelial lining but are delimited by fibroblasts and histiocytic cell forms at varying stages of differentiation. These cell forms are also the main component of the mononuclear stroma cells of the septa between the aneurysmal cavities. From these findings it is concluded that the aneurysmal cavities are not vascular. The sinusoidal septal capillaries might play a special role in their pathogenesis. Due to the lack of basal membrane structures, rupture of the wall gives rise to erythrocyte extravasates, which can undergo secondary transformation into cysts.

Fibrinolytic activity in aneurysmal bone cysts.

Euglobulin fibrinolytic activity of cyst fluid from six patients with aneurysmal bone cysys was considerably higher than that of arterial and venous blood of the corresponding patients. The high fibrinolytic activity was associated with a very low concentration of fibrinogen and a low concentration of plasminogen. Correspondingly, a high plasminogen activator activity was found in cyst tissue related to endothelial lining. It is suggested that fibrinolysis is an important factor in the maintenance and expansion of the aneurysmal bone cyst.

Increased concentrations of nitrate and nitrite in the cyst fluid suggesting increased nitric oxide synthesis in solitary bone cysts.

The etiology and treatment of a solitary bone cyst have remained undefined. Surgical treatments have not been encouraging, because a less invasive corticosteroid-injection treatment has afforded good results. However, there has been little scientific rationale supporting corticosteroid treatment. In recent reports, bone-resorbing factors, including matrix metalloproteinases, prostaglandins, interleukin-1, and oxygen free radicals, have been demonstrated in the cyst fluid. To better elucidate the pathophysiology of the solitary bone cyst, we examined the activities of nitric oxide and cytokines in the cyst fluid as well as in the cyst membrane. The levels of nitrate and nitrite were significantly higher in the cyst fluid than in serum. Immunostaining of cells in the stroma and lining cells of the cyst wall was strongly positive for inducible nitric synthase. The levels of interleukin-6 and interleukin-1beta in the cyst fluid were elevated, and cells in the cyst membrane were positive for tumor necrosis factor-alpha, interleukin-6, and interleukin-1beta. Cultured cells from the cyst membrane were induced in the production of nitrate and nitrite in response to cytokine treatment. These findings suggest that the solitary bone cyst was in a state favorable for the production of nitric oxide.

Expression of VEGF and MMP-9 in giant cell tumor of bone and other osteolytic lesions.

This study aims to investigate the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in giant cell tumor of bone (GCT) and other osteolytic lesions in bone. By using semi-quantitative RT-PCR, we showed that three major isoforms of VEGF (121, 165 and 189) were expressed in GCTs, with isoform 121 being the most abundant. The expression levels of VEGF and MMP-9 mRNA were significantly higher in advanced GCTs (stage II/III) than in stage I GCTs. We further elucidated the cellular localization of VEGF and MMP-9 gene transcripts in GCT and other osteolytic lesions using an in situ hybridization assay. The results showed that stromal tumor cells and osteoclast-like giant cells of GCT, fibrous stromal cells in anuerysmal bone cysts and fibrous dysplasia, and Langerhans-type giant cells as well as histocytes in eosinophillic granuloma, were all strongly positive for VEGF and MMP-9 mRNA expression. In a prospective study, we performed VEGF and MMP-9 immuno-staining on paraffin sections of pathological tissues harvested from 48 patients (14 GCT, 10 anuerysmal bone cysts, 10 eosinophillic granuloma, 4 fibrous dysplasia, 2 simple bone cyst, 2 osteomyelitis and 6 patients with fractured femoral head as control). The results showed that the differences in VEGF and MMP-9 expression between Stage I and other advanced Stages (II, III and recurrent) were highly significant (p<0.001), with advanced stages showing a higher mean expression. The difference between recurrent and Stage II and III lesions, was also statistically significant (p=0.03 for VEGF, and p=0.01 for MMP-9 expression), with recurrent lesions showing a higher mean expression of both VEGF and MMP-9. In conclusion, VEGF and MMP-9 expression in osteolytic lesions of bone co-relates well with the extent of bone destruction and local recurrence. Their expression may therefore provide some prognostic indication of the possible aggressive behavior of the underlying pathology.

The giant cholesterol cyst of the petrous apex: a distinct clinical entity.

The giant cholesterol cyst (GCC) of the petrous apex may now be considered a distinct clinical entity and should be considered in the differential diagnosis of lesions of the midcranial skull base. This benign cystic lesion of the petrous apex gradually enlarges and may produce progressive bone erosion and serial neurologic deficits of the cranial nerves within the temporal bone and jugular foramen. We report here five instances of this lesion (3 patients with unilateral and 1 patient with bilateral petrous apex lesions) and describe the natural history, diagnostic evaluation, pathology, and surgical management.

Evidence for fibroblasts as the major source of prostacyclin and prostaglandin synthesis in dental cyst in man.

Periodontal cysts synthesize large amounts of prostaglandins and collagenase which probably cause the localized bone destruction essential for intraosseous cyst growth. Fragments of cyst wall, and fibroblasts cultured from them, synthesized prostacyclin (PGI2) in addition to prostaglandin E2 (PGE2), PGF2 alpha and collagenase in vitro. Soluble products from cultures of unstimulated and phytohaemagglutinin-stimulated blood mononuclear cells enhanced the synthesis of these prostaglandins in monolayer cultures of cyst-wall fibroblasts. It is therefore proposed that cyst capsule fibroblasts are the major source of these bone-resorbing factors, acting under the stimulus of lymphocytes and monocytes in chronically inflamed cysts. Cysts which were not infiltrated by chronic inflammatory cells (follicular cysts, a keratocyst, an ameloblastoma, and an aneurysmal bone cyst) also produced prostaglandins and collagenase, indicating that the stimulatory mechanism for the production of bone-resorbing factors in these cysts may differ from that in periodontal cysts.

Membranous lipodystrophy of bone.

A 23-year old man with a fracture of the right lateral malleolus was found to have osteolytic lesions of the lower end of both fibulas and of the right talus. He was mentally defective from birth, with convulsions from the age of 4 years and a limp since the age of 15. Biopsy tissue from the right fibula that was removed one year after the fracture consisted of marrow adipose tissue that had been transformed by the development of thick, convuluted PAS positive membranes around the cells. Electron microscopy indicated that each membrane had a complex, microvillous substructure. At the time of biopsy, lytic lesions were found in both femoral medial condyles and, one year later, in the distal shaft of the left radius. Membranous lipodystrophy is a rare, generalized, skeletal disease that was previously reported in Finland and Japan, and is usually followed by progressive presenile dementia.

Upregulation of mRNA of interleukin-1 and -6 in subchondral cystic lesions of four horses.

This study investigated the potential association of interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in subchondral cystic lesions (SCL) in horses. With the technique of in situ hybridisation in paraffin sections of fibrous tissue of SCL and quantitative real-time PCR in fresh frozen fibrous tissue and undecalcified bone sections of SCL embedded in acrylic resin, upregulation of mRNA of both cytokines could be demonstrated. mRNA of IL-1beta was upregulated at the periphery of the cystic lesion adjacent to normal bone, whereas IL-6 mRNA was upregulated within the fibrous tissue found within the centre of the SCL. It was concluded that both cytokines are associated in pathological bone resorption observed in SCL and, in combination with increased production of prostaglandin E2, may be responsible for the slow healing, maintenance or further expansion of the cystic lesions.

A seminal vesicle cyst complicated with a tumor like nodular mass of benign proliferating prostatic tissue: a case report with ultrastructural and immunohistochemical studies.

We report a seminal vesicle cyst complicated with a tumor-like nodular mass of benign proliferating prostatic tissue. The patient was a 53-year-old Japanese man. A cyst of approximately 4.5 cm in diameter was discovered at the left seminal vesicle area. In the inner part of the cyst, a papillary nodular mass of 0.7 cm in diameter was seen. Under the clinical diagnosis of a seminal vesicle cyst with a tumorous mural nodule, the patient underwent resection of the seminal vesicle cyst to rule out the possibility that the nodular mass in the cyst was a neoplasm of an especially malignant nature. Microscopic examination of the excised specimen revealed a small dome-like nodular mass on the luminal surface of the cyst consisting of nodular proliferation of benign tubular gland tissue with various configurations. Conventional histologic, immunohistochemical, and ultrastructural analysis showed the proliferating cells in the nodular mass consisted of the benign prostate type. It is extremely important to differentiate between a benign proliferation and a malignant one, when the nodular mass is found in the seminal vesicle cyst.

High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo.

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 µg/mL, total dose 0.375 and 0.75 µg in 75 µg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 µg/mL, total dose 2.25 µg in 75 µg total volume), and a high BMP2 concentration range (150, 300, and 600 µg/mL, total dose 11.25, 22.5, and 45 µg in 75 µg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 µg/mL.

If good things come from above, do bad things come from below?

Factors in the synovial fluid that maintain healthy articular cartilage, such as hyaluronic acid and lubricin, come from above. Is it possible that factors which lead to the destruction of cartilage come from below in the subchondral bone? The recent acquisition of tools to probe early events in osteoarthritis is shedding new light on possible contributions from this compartment on the initiation and progression of the disease. Tanamas and co-workers now provide evidence that bone marrow lesions in the subchondral bone are predictive, both of loss of cartilage and of formation of subchondral cysts. These data provoke questions about the nature and role of bone marrow lesions.