Bone Infarct Associated Osteosarcoma: Epidemiologic and Survival Trends

A Rare Case of Multiple Bone Infarctions and Abnormal Pulmonary Function Tests in a Patient With Compound Heterozygous Hemoglobin S and Type 2 Hereditary Persistence of Fetal Hemoglobin

Sickle cell disease (SCD) is a group of inherited blood disorders characterized by abnormal hemoglobin production, affecting individuals worldwide with varying prevalence across different populations. Manifestations vary, ranging from severe to mild. SCD is characterized by the presence of hemoglobin S (HbS), which distorts erythrocytes upon deoxygenation, leading to sickling. This results in hemolytic anemia, painful vaso-occlusive crises (VOC), and multiple organ damage, including bones, due to microinfarcts. Sickle cell trait (SCT), or carrier status, is not considered an SCD and often runs a benign course. We report a 44-year-old man of African descent presenting with a one-month history of pain in his ankles and feet. He had a prior diagnosis of sickle cell "trait" without previous VOC. Hematological indices were normal. Hemoglobin electrophoresis showed absent HbA, elevated HbS, elevated HbF, and normal HbA2. X-rays and MRI revealed bilateral bone infarction in diaphyses of right proximal and bilateral distal tibias. Molecular analysis of [Formula: see text]-globin revealed compound heterozygous hemoglobin S and type 2 deletion of persistence of fetal hemoglobin (HPFH). Pulmonary function tests revealed restrictive lung disease. A literature review from 1946 to May 2024 via PubMed, EMBASE, and Medline was performed, revealing two cases of HbS-HPFH with avascular necrosis affecting the femoral neck were briefly reported more than 60 years ago. Although pulmonary function tests in SCD typically show a mild restrictive pattern with decreased diffusion capacity and rarely an obstructive pattern, no cases of HbS-HPFH were identified. In conclusion, multiple bone infarctions are extremely rare in HbS-HPFH. Lung and bone diseases might be unrecognized in this unique disorder.

Genomic Insights Into High-Grade Infarct-Associated Bone Sarcomas

Sarcomas rarely develop in bones previously compromised by infarcts. These infarct-associated sarcomas often present as undifferentiated pleomorphic sarcomas (UPS), and their genetic characteristics are poorly understood. High-grade UPS of bone are typically treated with a combination of surgery and chemotherapy, similar to osteosarcoma. We conducted a detailed clinicopathologic and genomic analysis of 6 cases of intraosseous sarcomas arising from histologically and radiographically confirmed bone infarcts. We analyzed 523 genes for sequence-level mutations using next-generation sequencing with the TruSight Oncology 500 panel and utilized whole-genome single nucleotide polymorphism Microarray (OncoScan CNV) to detect copy number alterations and loss of heterozygosity (LOH). Genomic instability was assessed through homologous recombination deficiency (HRD) metrics, incorporating LOH, telomeric allelic imbalance, and large-scale state transitions. Fluorescence in situ hybridization and immunohistochemistry validated the findings. The cohort included 3 men and 3 women, with a median age of 70 years, and tumors located in the femur and tibia. Five of the 6 patients developed distant metastases. Treatment involved surgery and chemotherapy or immune checkpoint inhibitors. Genomic analysis revealed significant complexity and high HRD scores, ranging from 32 to 57 (with a cutoff of 32). Chromosome 12 alterations, including segmental amplification or chromothripsis, were observed in 4 cases. Notably, MDM2 amplification, confirmed by fluorescence in situ hybridization, was detected in 2 cases. Homozygous deletion of CDKN2A/B was observed in all six cases. Tumor mutational burden levels ranged from 2.4 to 7.9 mutations per megabase. Notable pathogenic mutations included H3-3A mutations (p.G35R and p.G35W), and mutations in HRAS, DNMT3A, NF2, PIK3CA, POLE, and TP53, each in one case. These results suggest that high-grade infarct-associated sarcomas of bone, whereas sharing high levels of structural variations with osteosarcoma, may exhibit potentially less frequent TP53 mutations and more common CDKN2A/B deletions. This points to the possibility that the mutation spectrum and disrupted pathways could be distinct from conventional osteosarcoma.

Bone Infarcts and Tumorigenesis—Is There a Connection? A Mini-Mapping Review

(1) Background: Avascular necrosis (AVN) may affect every part of the bone. Epiphyseal infarcts are likely to be treated early because most are symptomatic. However, meta- and diaphyseal infarcts are silent and are diagnosed incidentally. Sarcomas developing in the necrotic bone are extremely rare, but they have been reported in the literature. (2) Methods: We conducted a mapping review of recent evidence regarding these malignancies. Methods: A mapping review using a systematic search strategy was conducted to answer research questions. We limited our research to the last ten years (2012–2022). (3) Results: A total of 11 papers were identified, including 9 case reports and 3 case series. The pathomechanism of carcinogenesis in AVN was not investigated to date. Histologically, most tumors were malignant fibrous histiocytoma. The prognosis is relatively poor, especially for patients with metastases, but adjuvant chemotherapy may increase short- and long-term survival. (4) Conclusions: Since AVN-related malignancies are sporadic, no prospective studies have been conducted. The majority of evidence comes from small case series. More research is needed to identify the risk factors that would justify follow-up of patients after bone infarcts at higher risk of developing a malignancy.