Intramuscular mesenchymal chondrosarcoma surrounded by a split fat sign mimicking a benign lesion.

Mesenchymal chondrosarcoma (MCS) is an aggressive malignant mesenchymal tumour of uncertain differentiation. This is rare, accounting for 2%-4% of chondrosarcomas. Its peak incidence is in the second and third decades, though it can occur at any age. These tumours show a widespread distribution, mainly in bone, but with approximately 40% affecting somatic soft tissue. We present a case of MCS arising within the soleus muscle. The lesion was surrounded by a split-fat sign/fatty rind which is a typical feature of peripheral nerve sheath tumours or other benign intramuscular tumours. However, percutaneous biopsy showed MCS. We highlight how perilesional fat is not exclusive to benign intramuscular lesions and, although much less common, can be associated with malignant lesions. This is, to the best of our knowledge, the first reported case of MCS presenting with a split-fat sign at MRI.

Mechanisms Underlying the Rarity of Skeletal Muscle Cancers.

Skeletal muscle (SKM), despite comprising ~40% of body mass, rarely manifests cancer. This review explores the mechanisms that help to explain this rarity, including unique SKM architecture and function, which prohibits the development of new cancer as well as negates potential metastasis to SKM. SKM also presents a unique immune environment that may magnify the anti-tumorigenic effect. Moreover, the SKM microenvironment manifests characteristics such as decreased extracellular matrix stiffness and altered lactic acid, pH, and oxygen levels that may interfere with tumor development. SKM also secretes anti-tumorigenic myokines and other molecules. Collectively, these mechanisms help account for the rarity of SKM cancer.

Management of Diaphragm Tumors.

Diaphragm tumors are very rare, with secondary tumors being more common than primary tumors. The most common benign primary tumors include lipomas and cysts, and malignant primary tumors include rhabdomyosarcoma and leiomyosarcoma. Endometriosis is the most common benign secondary tumor, followed by malignant tumors with localized spread of disease. In addition, widely metastatic disease has been described. Benign lipomas and cysts can be managed conservatively, but more complex or concerning disease typically requires resection. The diaphragm can often be repaired primarily, though any large defect or tension would indicate the need for mesh or an autologous reconstruction.

Cortical hypertrophy in intramuscular hemangioma mimicking bone tumor.

Although hemangiomas are the most common soft tissue tumors, intramuscular hemangiomas account for only 0.8% of all vascular tumors. These lesions are rarely located adjacent to the bone and cause changes in the adjacent bone. They are often mistakenly diagnosed as bone tumors. In this study, a case of a 19-year-old male patient with intramuscular hemangioma causing cortical thickening was reported.

Unique Case of Rare Non-Neural Granular Cell Tumor of the Rectus Abdominis Muscle.

Background and Objectives: Our report contributes a unique case of a non-neural GCT occurring in an unusual location, with its development during pregnancy adding to its rarity. Materials and Methods: Granular cell tumors (GCTs), also known as Abrikossoff's tumors, are rare neoplasms of Schwann cell origin with predominantly benign behavior. We present a case of a 29-year-old female with a non-neural variant of a GCT discovered incidentally during a cesarean section, situated on the posterior surface of the rectus abdominis muscle. Results: Histologically, the tumor exhibited features consistent with a benign non-neural GCT, confirmed through an immunohistochemical analysis. Despite the atypical presentation and challenging surgical removal due to prior scarring, the patient experienced no postoperative complications and showed no signs of recurrence during follow-up. Conclusions: This case highlights the importance of considering GCTs in differential diagnoses, particularly in unusual anatomical locations, and underscores the favorable prognosis associated with timely surgical intervention.

Inflammatory Rhabdomyoblastic Tumor: From a Nebulous Smooth Muscle Neoplasm to a Novel Skeletal Muscle Tumor Subtype.

Inflammatory rhabdomyoblastic tumor is a recently introduced name for neoplasms currently included in the World Health Organization classification of soft tissue tumors under the rubric inflammatory leiomyosarcoma. Inflammatory rhabdomyoblastic tumor is an excellent example of how surgical pathologists working in conjunction with tumor biologists can greatly improve tumor classification to the benefit of patients. Over the last 28 years, understanding of this entity has undergone a fascinating evolution. This review serves as a summary of the latest findings in inflammatory rhabdomyoblastic tumor research and a diagnostic manual for the practicing surgical pathologist.

LMNA::NTRK1 Fusion-positive Leiomyosarcoma: Discrepancy between DNA-based Comprehensive Genomic Profiling and RNA Sequencing.

A 26-year-old man presented with a tumor in the left soleus muscle. The tumor was diagnosed as a locally advanced leiomyosarcoma. The patient was treated with irradiation followed by wide resection. One year after surgery, the patient presented with multiple lung metastases. Despite aggressive sequential chemotherapy, systemic metastatic tumors continued to develop. To explore therapeutic options for the patient, we performed DNA-based CGP with FoundationOne® CDx (F1). F1 identified an out-of-strand rearrangement of the NOS1AP::NTRK1 gene, which has not been previously reported. In contrast, RNA sequencing revealed an in-frame LMNA::NTRK1 gene, which is an oncogenic fusion gene.

Cotyledonoid dissecting leiomyoma of the uterus: a case report and review of the literature.

BACKGROUND: Cotyledonoid dissecting leiomyoma, also named Sternberg tumor, is a rare variant of uterine leiomyoma. The tumor is benign, but the appearance and growth pattern are unusual and alarming. In this article, we report a case of cotyledonoid dissecting leiomyoma in a 55-year-old woman as well as review relevant literature. CASE PRESENTATION: We report a case of cotyledonoid dissecting leiomyoma in a 55-year-old Iranian woman who presented with vaginal bleeding 4 months after menopause. Ultrasound showed two heterogeneous hypoechoic masses on the uterine fundus. Total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed for the patient. Macroscopically, a large heterogeneous intramural mass (140 mm × 120 mm × 120 mm) with a grape-like exophytic mass on the fundus was observed. Her health status was good after surgery, and the patient was discharged from the hospital after 2 days. In a 1-year follow-up period, no recurrence or any other related complications were found. CONCLUSION: It is important to recognize this rare variant of leiomyoma to prevent aggressive and inappropriate overdiagnosis and overtreatment. It is suggested to try to use frozen sections for better diagnosis and to preserve fertility in young women suffering from this lesion.

Laparoscopic resection of a rare diaphragmatic haemangioma: a case report.

This case report describes the laparoscopic resection of a rare diaphragmatic haemangioma. A 45-year-old male patient was diagnosed incidentally with a left subphrenic mass by computed tomography. Laparoscopic left subphrenic mass excision was performed under general anaesthesia. A phrenic haemangioma was confirmed by postoperative pathology. Tumours originating in the diaphragm are rare, with only approximately 200 cases reported in the past century. The diaphragmatic tumour was determined to be primary because intraoperative imaging showed that the tumour was relatively isolated and had no obvious relationship with the surrounding tissues and organs.

Primary seminal vesicle epithelioid smooth muscle neoplasm of uncertain biologic potential.

We present the case of a 73-year-old male patient who presented with obstructive urinary symptoms, pelvic pressure, and hematuria. CT imaging revealed a heterogenous prostate enlargement, and MRI demonstrated the mass to be arising from the seminal vesicle. Prostate biopsies showed benign tissue. Surgical excision was completed and pathology revealed it to be an epithelioid smooth muscle neoplasm of uncertain biologic potential. This is only the second known case of such a seminal vesicle tumour. As soft tissue sarcomas of the seminal vesicle emerge in the literature, we may develop a better understanding of their biologic behaviour and prognostic potential.

[Histiocyte-rich rhabdomyoblastic tumor: a clinicopathological and molecular genetic analysis].

Objective: To investigate the clinicopathologic and molecular genetic characteristics, diagnosis, differential diagnosis, treatment and prognosis of histiocyte-rich rhabdomyoblastic tumor (HRRMT). Methods: The clinical data of two cases of HRRMT diagnosed in Fujian Provincial Hospital and Fujian University of Traditional Chinese Medicine Affiliated People's Hospital from 2020 to 2021 were collected. Histopathology and immunohistochemical (IHC) staining were used to assess morphological changes; the genetic changes were analyzed with next-generation sequencing. The relevant literature was reviewed. Results: Both cases showed well-defined solid nodules and soft masses. Microscopically, the tumors had a fibrous pseudocapsule with lymphocytic aggregation, and locally invaded the surrounding skeletal muscle tissue, and the tumor cells were fusiform to epithelioid with an intensive foamy histiocytic infiltrate. No necrosis or mitosis was observed. Immunophenotyping showed the tumor cells were positive for desmin, either one or both skeletal muscle markers (myogenin or MyoD1), and negative for h-caldesmon, ALK and SMA. The Ki-67 index was<5%. Using next-generation sequencing, one case was found to harbour KRAS (G12D) and MSH3 (Q470*) mutations. Conclusions: HRRMT is a newly described skeletal muscle tumor with uncertain malignant potential. Its diagnosis and differential diagnosis depend on morphologic and IHC staining. No specific molecular genetics changes have been identified so far.

A case of intramuscular lumbar myxoma: Uncertainty in the preoperative diagnosis of a spinal soft tissue tumour.

We report an uncommon case of a 76-year-old woman who presented with lower back pain, an intermittent L5 radiculopathy and a right palpable paraspinal mass. Imaging studies revealed a 7-cm lumbar paraspinal pseudo-cystic soft tissue tumour developed in the paravertebral musculature, without a clear radiological diagnosis. Gross total surgical resection was performed, resulting in complete resolution of pain. Histopathological studies revealed an intramuscular (IM) myxoma. With a low positive predictive value of radiological work-up and a poor yield of percutaneous biopsies, surgery remains the mainstay treatment for these rare soft tissue tumours of the lumbar spine. Intramuscular myxomas show excellent postoperative results.

CRTC1-SS18 Fusion Sarcoma With Aberrant Anaplastic Lymphoma Kinase Expression.

Undifferentiated small round cell sarcoma (USRCS) represents a highly heterogeneous group of tumors. A variety of specific gene fusions of USRCS have been reported, including CIC-FOXO4, CIC-NUTM1, BCOR-MAML3, and ZC3H7B-BCOR. Here we report a case of sarcoma harboring a rare recurrent CRTC1-SS18 gene fusion, which was considered as USRCS previously. This sarcoma was composed of nests of small round cells encapsulated in a fibrous stroma. Foci of necrosis and hemorrhage were observed in the tumor. Immunohistochemistry for anaplastic lymphoma kinase showed diffuse positivity. RNA-seq results revealed a chromosomal translocation of CRTC1 gene exon 1 on chromosome 19 with SS18 gene exon 2 on chromosome 18. Thereafter, fluorescence in-situ hybridization confirmed the presence of SS18 gene and CRTC1 gene break-apart, which manifested as the splitting of red and green signals into 2 parts. A previous study showed that CRTC1-SS18 fusion sarcoma and EWSR1-CREB1 fusion angiomatoid fibrous histiocytoma were clustered close in the expression profile. However, whether CRTC1-SS18 fusion sarcomas represent a high malignancy has been a matter of debate. Our study is a worthy addition to the series of rare rearrangements associated with sarcomas and may be of therapeutic relevance.

Latency-associated peptide identifies therapeutically resistant muscle-invasive bladder cancer with poor prognosis.

BACKGROUND: Latency-associated peptide (LAP) was identified as crucial immune regulator in tumor microenvironment (TME) in recent researches. In this study, we aimed to estimate the predictive value of LAP expression for clinical survival and therapeutic response in muscle-invasive bladder cancer (MIBC). METHODS: Our study encompassed 140 MIBC patients from Zhongshan Hospital (ZSHS cohort), 401 patients from The Cancer Genome Atlas (TCGA cohort) and 195 patients received PDL1 blockade from IMvigor210 trial. Survival analyses were conducted through Kaplan-Meier curve and Cox regression model. LAP expression and its association with immune contexture were evaluated in ZSHS and TCGA cohort. RESULTS: We found that high intratumoral LAP+ cells infiltration anticipated inferior survival and adjuvant chemotherapy (ACT) response, and was closely related to an immunoevasive contexture with increased M2 macrophages, neutrophils and conspicuously a cluster of highly exhausted CD8+ T cells. The combinational analysis of LAP+ cells and CD8+ T cells infiltration stratified patients into distinct risk groups with implications for therapeutic sensitivity to PDL1 blockade and refinement of molecular classification in MIBC. CONCLUSIONS: LAP expression was correlated with patients' inferior prognosis, ACT-tolerance and an immunoevasive TME with exhausted CD8+ T cell infiltration, suggesting that LAP could serve as a promising therapeutic target in MIBC. Simultaneously, our novel TME classification based on LAP+ cells and CD8+ T cells infiltration and its potential in appraising PDL1 blockade application for MIBC patients deserved further validation.

The impact of patient sex on characteristic-adjusted bladder cancer prognosis.

CONTEXT: Bladder cancer is one of the most common malignancies worldwide. Some studies noted sex differences in the prognosis of bladder cancer, but results are inconsistent. SUBJECTS AND METHODS: In this study, we assessed whether women with bladder cancer exhibit a worse prognosis, after adjustment for disease stage, age, and body mass index (BMI), using clinical data from The Cancer Genome Atlas. We used a Student's t-test to compare age and BMI in groups with different sexes. STATISTICAL ANALYSIS USED: The Kaplan-Meier method with log-rank test was used to determine clinical prognosis. RESULTS: The BMI (30.15 vs. 26.68, P = 0.0035) and age (67.54 years vs. 66.01 years, P = 0.045) of female patients with muscle-invasive bladder cancer (MIBC) were higher than those of male patients. The overall survival (OS) prognosis of female patients was worse than that of male patients. After grouping by disease characteristics, the disease-free survival (DFS) and OS prognoses of female patients under 60 years of age were worse than those of male patients. In the group with BMI >24, the OS prognosis of female patients was worse than that of male patients, but no difference was found in DFS prognosis. In the group with BMI ≤24, the DFS prognosis of female patients was worse than that of male patients, but no difference was found in OS prognosis. Compared to males, female patients with Stage III disease demonstrated a worse DFS prognosis and poorer OS prognosis, women with stage T3 demonstrated a worse DFS prognosis, and women with stage N0 demonstrated a poorer OS prognosis. No difference was found in prognosis between male and female patients in all other groups. CONCLUSIONS: In patients with MIBC, women tended to exhibit a worse prognosis than men. More specifically, we found a correlation between prognosis and sex after grouping patients by BMI.

Standard diffusion-weighted, intravoxel incoherent motion, and dynamic contrast-enhanced MRI of musculoskeletal tumours: correlations with Ki67 proliferation status.

AIM: To determine whether quantitative parameters derived from conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) correlate with the Ki67 proliferation status in musculoskeletal tumours. MATERIALS AND METHODS: Twenty-eight patients with musculoskeletal tumours diagnosed via surgical specimen histological analysis who underwent standard DWI, IVIM, and DCE were reviewed retrospectively. The mean standard DWI (apparent diffusion coefficient [ADC]), IVIM (pure diffusion coefficient [D], pseudo-diffusion coefficient [D∗] and perfusion fraction [ƒ]), and DCE (volume transfer constant [Ktrans], rate constant [Kep], and extravascular extracellular volume fraction [Ve]) parameters were measured and correlated with the Ki67 index. The Ki67 value was categorised as high (>20%) or low (≤20%). RESULTS: The ADC and D values correlated negatively with the Ki67 index (r=-0.711∼-0.699, p<0.001), whereas the Ktrans and Kep values correlated positively with the Ki67 index (r=0.389-0.434, p=0.021, 0.041). The ADC and D values were lower (p<0.001), whereas the Ktrans and Kep values were higher (p=0.011, 0.005) in musculoskeletal tumours with a high Ki67 status than in those in a low status. The ADC and D demonstrated the largest area under the receiver-operating characteristic curve (AUC = 0.953), which is statistically bigger than the AUC of Ktrans and Kep (0.784 and 0.802, respectively). CONCLUSION: ADC, D, Ktrans, and Kep correlate with the Ki67 index. ADC and D are the strongest quantitative parameters for predicting Ki67 status.