No abstract

Calcific myonecrosis is a rare soft tissue condition. The first case was reported in 1960, however, the precise pathophysiology of calcific myonecrosis remains unclear. The disease was thought to arise from compartment syndrome within a confined space resulting in necrosis and fibrosis, subsequent repeated intralesional hemorrhage, mass enlargement and calcification. Several previous reports have described calcific myonecrosis, which include the formation of calcific myonecrosis after a prolonged period of post trauma. Notably, calcific myonecrosis has typically been described in the lower legs and characteristic imaging findings have been indicated. Furthermore, surgical intervention carries a high risk of complications. In the present case report 2 cases of calcific myonecrosis that occurred after a prolonged period of time following a traumatic event that impacted the lower leg were reported. CT images revealed disruption of calcified fascia and disease expansion into the outside of the fascia. Previous reports have implied that there is late focal enlargement of calcific myonecrosis following earlier enlargement, which may be caused by herniation through muscle fascia. However, no previous publications have focused on images for evidence of late local enlargement. To the best of our knowledge, this is the first report focusing on fascial herniation of calcific myonecrosis using images. Analysis of this feature using images may aid clinicians to differentiate calcific myonecrosis from malignancies.

Objective: The nucleus pulposus (NP) comprises notochordal NP cells (NCs) and chondrocyte-like NP cells (CLCs). Although morphological similarities between CLCs and chondrocytes have been reported, interactions between CLCs and NCs remain unclear. In this study, we aimed to clarify regulatory mechanisms of cells in the NP and chondrocytes.Design: We performed single-cell RNA sequencing (scRNA-seq) analysis of the articular cartilage (AC) and NP of three-year-old cynomolgus monkeys in which NCs were present. We then performed immunohistochemical analysis of NP and distal femur. We added sonic hedgehog (SHH) to primary chondrocyte culture.Results: The scRNA-seq analysis revealed that CLCs and some articular chondrocytes had similar gene expression profiles, particularly related to GLI1, the nuclear mediator of the hedgehog pathway. In the NP, cell–cell interaction analysis revealed SHH expression in NCs, resulting in hedgehog signaling to CLCs. In contrast, no hedgehog ligands were expressed by chondrocytes in AC samples. Immunohistochemical analysis of the distal end of femur indicated that SHH and Indian hedgehog (IHH) were expressed around the subchondral bone that was excluded from our scRNA-seq sample. scRNA-seq data analysis and treatment of primary chondrocytes with SHH revealed that hedgehog proteins mediated an increase in hypoxia-inducible factor 1-alpha (HIF-1α) levels.Conclusion: CLCs and some articular chondrocytes have similar transcriptional profiles, regulated by paracrine hedgehog proteins secreted from NCs in the NP and from the subchondral bone in the AC to promote the HIF-1α pathway.

Malignant peripheral nerve-sheath tumors (MPNSTs) are rare malignancies that are often observed in patients with neurofibromatosis type 1 (NF1). However, the occurrence of MPNST associated with mosaic localized NF1 is extremely rare. Previous reports have revealed that MPNST was associated with mosaic localized NF1 in only three patients who were >40 years of age. The present report details a 16-year-old man who presented with pain and a 3 cm mass on the medial side of the right knee. Magnetic resonance imaging revealed a circumscribed soft tissue tumor located in the subcutaneous tissue. His previous doctor believed that it was benign and conducted a marginal resection. However, postoperative histology results demonstrated spindle cell sarcoma, following which the patient was referred to The Osaka International Cancer Institute. Localized café-au-lait spots were identified in the affected leg, which inferred that the patient had NF1-related MPNST. A wide resection was performed to completely resect the residual tumor; however, a definitive histological diagnosis was challenging due to the small residual tumor. Hence, the genomic mutations of NF1 in the regional café-au-lait spots were analyzed. The result revealed an NF1 microdeletion and a consistently limited expression of NF1 in the tumor sample. Finally, the patient was diagnosed with MPNST with mosaic localized NF1. Local recurrence and distant metastasis were not observed 1.5 years after surgery. In conclusion, the present report presented MPNST in an adolescent patient with mosaic localized NF1. The occurrence of MPNSTs correlated with mosaic localized NF1 is extremely rare. However, it is of high-grade malignancy and therefore, its clinical features should be considered by orthopedists and pathologists.