Coordination of bone morphogenetic protein 2 (BMP2) and aberrant canonical Wnt/β-catenin signaling for heterotopic bone formation in adrenal myelolipoma: A case report

Involvement of the Wnt/β-catenin signalling pathway in heterotopic ossification and ossification-related diseases

Heterotopic ossification (HO) is a pathological condition characterized by the formation of bone within soft tissues. The development of HO is a result of abnormal activation of the bone formation programs, where multiple signalling pathways, including Wnt/β-catenin, BMP and hedgehog signalling, are involved. The Wnt/β-catenin signalling pathway, a conserved pathway essential for various fundamental activities, has been found to play a significant role in pathological bone formation processes. It regulates angiogenesis, chondrocyte hypertrophy and osteoblast differentiation during the development of HO. More importantly, the crosstalk between Wnt signalling and other factors including BMP, Hedgehog signalling, YAP may contribute in a HO-favourable manner. Moreover, several miRNAs may also be involved in HO formation via the regulation of Wnt signalling. This review aims to summarize the role of Wnt/β-catenin signalling in the pathogenesis of HO, its interactions with related molecules, and potential preventive and therapeutic measures targeting Wnt/β-catenin signalling.

Inhibition of IL-17 prevents the progression of traumatic heterotopic ossification

Traumatic heterotopic ossification (HO) is the abnormal formation of bone in soft tissues as a consequence of injury. However, the pathological mechanisms leading to traumatic HO remain unknown. Here, we report that aberrant expression of IL-17 promotes traumatic HO formation by activating β-catenin signalling in mouse model. We found that elevated IL-17 and β-catenin levels are correlated with a high degree of HO formation in specimens from patients and HO animals. We also show that IL-17 initiates and promotes HO progression in mice. Local injection of an IL-17 neutralizing antibody attenuates ectopic bone formation in a traumatic mouse model. IL-17 enhances the osteoblastic differentiation of mesenchymal stem cells (MSCs) by activating β-catenin signalling. Moreover, inhibition of IL-17R or β-catenin signalling by neutralizing antibodies or drugs prevents the osteogenic differentiation of isolated MSCs and decreases HO formation in mouse models. Together, our study identifies a novel role for active IL-17 as the inducer and promoter of ectopic bone formation and suggests that IL-17 inhibition might be a potential therapeutic target in traumatic HO.

Primary hepatic myelolipoma: A case report and review of the literature

BACKGROUND

Primary hepatic myelolipoma is a rare hepatic mesenchymal tumor mixed by adipose tissue and bone marrow, and there is a lack of general guidelines related to its epidemiology and clinical management.

CASE SUMMARY

A 26-year-old woman was admitted to our department complaining of a newly found tumor on her left lobe of the liver. The tumor was painless and not associated with any systemic or localized compressive symptoms. Serological tests disclosed a slight increase of gamma-glutamyl transpeptidase (70.0 U/L) and total bilirubin (19.2 μmol/L). Ultrasonography showed a mass about 5.0 cm × 5.0 cm in size that was located in the left lobe of the liver and displayed hyperechoic and well-encapsulated characteristics. Surgical resection was applied, and the following histopathological examination observed a variable proportion of myeloid tissues scattering throughout mature fibrotic adipose tissues, in which myeloid, erythroid, and megakaryocytic cells can be found in magnified view. The follow-up did not show any changes 6 mo after surgery.

CONCLUSION

This case highlights an extremely rare hepatic mesenchymal tumor, the primary hepatic myelolipoma, and discloses the common characteristics behind this disease and gives clinical recommendations.

Heterotopic ossification of tendon and ligament

Much of the similarities of the tissue characteristics, pathologies and mechanisms of heterotopic ossification (HO) formation are shared between HO of tendon and ligament (HOTL). Unmet need and no effective treatment has been developed for HOTL, primarily attributable to poor understanding of cellular and molecular mechanisms. HOTL forms via endochondral ossification, a common process of most kinds of HO. HOTL is a dynamic pathologic process that includes trauma/injury, inflammation, mesenchymal stromal cell (MSC) recruitment, chondrogenic differentiation and, finally, ossification. A variety of signal pathways involve HOTL with multiple roles in different stages of HO formation, and here in this review, we summarize the progress and provide an up‐to‐date understanding of HOTL.

Adrenal Myelolipomas Involved by Plasma Cell Myeloma

OBJECTIVES

To report the presence and evaluate the frequency of plasma cell neoplasms within adrenal myelolipomas.

METHODS

Adrenal myelolipomas within our institution were reviewed for the presence of hematologic neoplasia, and a review of the literature was performed.

RESULTS

Two (9%) of 23 adrenal myelolipomas were involved by plasma cell myeloma. The patients were 71 and 81 years old, one woman and one man, with tumors measuring 7 cm and 8.5 cm, respectively. Both tumors contained large aggregates of dysplastic plasma cells occupying at least one ×10 field and demonstrated light chain restriction. Neither had an established diagnosis of plasma cell neoplasm previously. After receiving therapy, one patient exhibited a stable clinical course 1 year after diagnosis while the other died of disease 3 years later.

CONCLUSIONS

We report the first two cases of adrenal myelolipoma involved by plasma cell myeloma, a rare and subtle finding that has significant clinical implications.

Conserved signaling pathways underlying heterotopic ossification

Heterotopic ossification (HO), a serious disorder of extra-skeletal bone formation, occurs as a common complication of trauma or in rare genetic disorders. Many conserved signaling pathways have been implicated in HO; however, the exact underlying molecular mechanisms for many forms of HO are still unclear. The emerging picture is that dysregulation of bone morphogenetic protein (BMP) signaling plays a central role in the process, but that other conserved signaling pathways, such as Hedgehog (HH), Wnt/β-catenin and Fibroblast growth factors (FGF), are also involved, either through cross-talk with BMP signaling or through other independent mechanisms. Deep understanding of the conserved signaling pathways is necessary for the effective prevention and treatment of HO. In this review, we update and integrate recent progress in this area. Hopefully, our discussion will point to novel promising, druggable loci for further translational research and successful clinical applications.

Update on Adrenal Tumours in 2017 World Health Organization (WHO) of Endocrine Tumours

The fourth edition of the World Health Organization (WHO) classification of endocrine tumours contains substantial new findings for the adrenal tumours. The tumours are presented in two chapters labelled as "Tumours of the adrenal cortex" and "Tumours of the adrenal medulla and extra-adrenal paraganglia." Tumours of the adrenal cortex are classified as cortical carcinoma, cortical adenoma, sex cord stromal tumours, adenomatoid tumour, mesenchymal and stromal tumours (myelolipoma and schwannoma), haematological tumours, and secondary tumours. Amongst them, schwannoma and haematological tumours are newly documented. The major updates in adrenal cortical lesions are noted in the genetics of the cortical carcinoma and cortical adenoma based on the data from The Cancer Genome Atlas (TCGA). Also, a system for differentiation of oncocytoma from oncocytic cortical carcinoma is adopted. Tumours of the adrenal medulla and extra-adrenal paraganglia comprise pheochromocytoma, paraganglioma (head and neck paraganglioma and sympathetic paraganglioma), neuroblastic tumours (neuroblastoma, nodular ganglioneuroblastoma, intermixed ganglioneuroblastoma, and ganglioneuroma), composite pheochromocytoma, and composite paraganglioma. In this group, neuroblastic tumours are newly included in the classification. The clinical features, histology, associated pathologies, genetics, and predictive factors of pheochromocytoma and paraganglioma are the main changes introduced in this chapter of WHO classification of endocrine tumours. The term "metastatic pheochromocytoma/paraganglioma" is used to replace "malignant pheochromocytoma/paraganglioma." Also, composite pheochromocytoma and composite paraganglioma are now documented in separate sections instead of one. Overall, the new classification incorporated new data on pathology, clinical behaviour, and genetics of the adrenal tumours that are important for current management of patients with these tumours.

Case Report: An incidentaloma that catches your eye - adrenal myelolipoma

Background: Adrenal incidentaloma refers to the incidental finding of a tumor in the adrenal gland, where nonfunctional forms are the most common variant. Myelolipoma is a rare (0.08-0.4%) occurrence characterized by adipose and hematopoietic tissue. The aim of this case report is to describe the diagnosis and appropriate management of a myelolipoma in an asymptomatic patient, which was originally considered an incidental hepatic hemangioma prior to being identified as a giant adrenal adenoma. Case description: The patient was a 54 year old obese female with a recent diagnosis of diabetes type II and dyslipidemia with recent ultrasound imaging suggestive of a hepatic hemangioma. An MRI was performed revealing a 7x6cm lesion in the right adrenal area indicating a giant adrenal adenoma. An adrenalectomy was performed without complications. The pathology report identified a myelolipoma. Discussion: The incidence of myelolipoma has recently increased due to advances in radiological techniques. Its etiology is unclear and the most accepted theories support a myeloid cell metaplasia in the embryonic stage as a result of stress, infections, or adrenocorticotropic hormone or erythropoietin stimulus. Contributing components may include bone morphogenetic protein 2 and β-catenin, as well as the presence of the chromosomal translocation (3, 21) (q25; p11). Despite its benign nature, the association with other adrenal lipomas must be ruled out. A biochemical evaluation is essential for detecting subclinical states, such as Cushing syndrome and pheochromocytoma. Conclusion: Adrenal myelolipomas are rare benign tumors that are generally asymptomatic. Uncertainty still exists surrounding their etiology. Surgical management depends on hormone production, tumor size, high risk features on imaging and patient consent.  Additional information is needed to better understand myelolipomas, their etiology, and clinical management.  Incidentalomas may confuse the physician and patient. Ensuring proper multidisciplinary management based on the clinical guidelines of endocrinology allowed a satisfactory resolution of this case.

Lipomatous tumours in adrenal gland: WHO updates and clinical implications

Adrenal lipomatous tumour is a group of adrenal tumours with a significant component of adipose tissue. According to the current World Health Organization (WHO) classification of tumours of endocrine organs, adrenal myelolipoma is the only entity amongst the group of tumours being described. In the literature, other more recently documented adrenal lipomatous tumours included 24 lipomas, 32 teratomas and 16 angiomyolipomas. Rare fatty tumours of the adrenal gland comprised liposarcoma, hibernoma, adrenocortical tumours with fat component and rare adrenal tumours with fat component. Myelolipoma comprises approximately 3% of primary adrenal tumour. It is noted more commonly in females and in the right adrenal gland. Approximately 40 bilateral myelolipomas were reported. The tumour is most frequently recorded in patients between fifth and seventh decades of life. Adrenal lipomas are often seen in males and in the right adrenal gland. They were commonly noted in patients in the sixth decade of life. The diagnosis could only be possible on examination of the surgically removed specimen. Adrenal teratomas were more common in females and with a bimodal age distribution. Slightly over 60% of the patients with adrenal teratoma are symptomatic. Adrenal angiomyolipomas were often symptomatic, more common in females and in the fifth decades of life. To conclude, adrenal lipomatous tumour is uncommon. They are often benign and non-functional. It is important to recognize the features of this group of lipomatous tumours in the adrenal gland as they are being detected on increasing incidence as a result of the wide-spread use of modern imaging modalities.

Fetuin A is down-regulated in rats during heterotopic ossification after Achilles tenotomy

We investigated the role of fetuin A during heterotopic ossification (HO) in rats following Achilles tenotomy. We performed a right midpoint Achilles tenotomy on 24 rats. At 5 and 10 h after surgery, we investigated the formation of ectopic bone using X-ray and histological examination. We evaluated the mRNA level of fetuin A using real-time PCR. Presence of fetuin A in the Achilles tendon was assessed by immunohistochemical staining. We also measured the serum concentration of fetuin A using enzyme linked immunosorbent assay (ELISA). The expression of fetuin A was significantly decreased in both the liver and Achilles tendon during HO. ELISA showed a small amount of fetuin A in blood throughout the development of HO. Immunohistochemical staining showed that fetuin A was abundant in the ectopic bone. Fetuin A appears to be involved in the formation of ectopic bone induced by Achilles tenotomy, and a deficiency of fetuin A plays a role in the development of HO.