Pulmonary metastases of a renal angiomyolipoma: A case report, with whole-exome sequencing analysis.

We present a case of pulmonary metastasis originating from renal angiomyolipoma (AML), as evidenced by whole-exome sequencing (WES) analysis. Although AML predominantly arises in the kidneys, it can emerge in various body parts, making it important to distinguish between multicentric development and metastasis. However, previous studies have not distinguished between these conditions. Our case features an 82-year-old woman with a history of renal AML who presented with multiple, randomly distributed, bilateral pulmonary nodules of varying size and pure fat densities. The patient's condition followed a benign course over 10 years. Through WES, we discovered shared mutations in pulmonary lesions that were absent in the patient's blood, including a pathological mutation in TSC2, suggesting a metastatic origin from renal AML. Knowledge of the pulmonary manifestations of AML and their distinctive imaging findings can help radiologists and clinicians diagnose and manage patients with similar presentations.

A case of robotic distal pancreatectomy for solitary fibrous tumor of the pancreas.

Solitary fibrous tumor (SFT) is a spindle cell tumor driven by the NAB2-STAT6 fusion gene. While it can originate from any soft tissue, primary SFT of the pancreas is rare with limited reports. A 36-year-old man came to our department due to abdominal pain. Computed tomography revealed a circular mass with weak peripheral enhancement and an internal cyst in the pancreatic tail. Diagnosis was not confirmed through endoscopic ultrasound-guided biopsy, and differential diagnoses included acinar cell carcinoma and pancreatic neuroendocrine tumor. A robotic distal pancreatectomy with splenectomy was performed, and the patient was discharged 11 days postoperatively. Histopathological examination showed an irregular arrangement of spindle cells, and immunohistochemical staining was positive for CD34 and STAT6, confirming an SFT diagnosis with low metastatic risk. Robotic surgery effectively managed this tumor.

Inflammatory spindle cell PEComa of the lung with YAP1::TFE3 fusion: a report of two cases and a potential relationship with clear cell stromal tumour.

AIMS: The PEComa family of tumours is defined by spindle/epithelioid cells with myomelanocytic differentiation. A small subset harbours TFE3 fusion; however, YAP1::TEE3 has not been reported. Clear cell stromal tumour of the lung (CCST-L) is an emerging entity characterized by spindle to epithelioid cells with focal cytoplasmic clearing, inflammatory infiltrates, no myomelanocytic differentiation, and YAP1::TFE3 fusion. Herein, we report two cases of lung tumours with myomelanocytic differentiation that showed inflammatory spindle cell histology, focal epithelioid clear cells, as well as YAP1::TFE3 fusion. METHODS AND RESULTS: The patients were both men, aged 61 and 68 years. The tumours in both cases presented as well-circumscribed solid masses involving the lung hilum. After lobectomy, no recurrence was observed at 7 and 32 months. Both tumours shared storiform to short fascicular growth of long spindle cells, with a minor component of epithelioid cells showing clear cytoplasm in the background of substantial intratumoral chronic inflammation and dilated blood vessels. One tumour showed focal melanin deposition. Both tumours were immunohistochemically positive for HMB45, Melan A, and h-caldesmon. Fluorescence in situ hybridization assays indicated the presence of YAP1::TFE3 fusions, which was confirmed by RNA sequencing in one case tested, and by immunohistochemical TFE3 expression and loss of YAP1 C-terminus staining. CONCLUSION: We present two cases of inflammatory spindle to epithelioid cell tumours of the lungs with myomelanocytic differentiation and YAP1::TFE3 fusion. This unique morphology and gene fusion suggest that these tumours may constitute a distinct subset of lung PEComa. Furthermore, morphological and molecular overlap with CCST-L gives rise to a hypothesis of a potential inherent relationship between PEComa and CCST-L.

The significance of T-BET-positive CD8 T-cells with diminished CD5 expression in Kikuchi-Fujimoto disease.

Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a rare condition characterized by benign localized lymphadenopathy and clinical symptoms such as fever, sore throat, odynophagia, and leukopenia. Though the etiology of KFD is unknown, this condition is similar to viral infection, including increased infiltration of activated plasmacytoid dendritic cells. KFD exhibits three histological phases that reflect its progression status: proliferative, necrotic, and xanthomatous lesions. The expression loss of pan T-cell markers, such as CD2, CD5, and CD7, of infiltrating T-cells is observed in KFD cases, complicating the distinction from T-cell lymphoma. However, reports on the loss of their expression in KFD have been limited. Furthermore, the precise population of the T-cell subset in KFD is still unclear. Here, we focused on surface markers and transcription factors for T-cell differentiation and analyzed them immunohistochemically in 46 KFD cases. We observed diminished CD5 expression of CD8-positive (CD5dim CD8+) T-cells in the proliferative lesion of KFD cases. Furthermore, these CD5dim CD8+ T-cells expressed T-BET, a master regulator of type 1 helper T-cells. The upregulation of T-BET and downregulation of CD5 in CD8+ T-cells causes dysregulated activation and proliferation of CD8+ T-cells, potentially contributing to the unique histopathological features of KFD. Recognizing the frequent infiltration of T-BET-positive CD5dim CD8+ T-cells in KFD is important for distinguishing it from mature T-cell lymphoma. Our findings suggest that the immune response in KFD shares similarities with viral infections and highlight the importance of characterizing T-BET-positive CD5dim CD8+ T-cell populations for understanding KFD pathogenesis.

Comment on Manole et al. Primary Pericardial Synovial Sarcoma: A Case Report and Literature Review. Diagnostics 2022, 12, 158.

With great interest, we read the article by Manole et al [...].

[Early Duodenal Cancer Resected by Using Laparoscopic and Endoscopic Assistance Surgery in a Patient with Peutz-Jeghers Syndrome].

A 28-year-old female with a history of treatment for small intestinal polyps and characteristic pigmentation of her lip was clinically diagnosed with Peutz-Jeghers syndrome(PJS). Her sister had the pathogenic variant of STK11 upon genetic testing. A 20-mm polyp was identified in the second part the patient's duodenum on routine gastrointestinal surveillance, and biopsy revealed a well-differentiated adenocarcinoma. Laparoscopic partial duodenectomy with endoscopy was planned. After confirming the location of the tumor and Kocherization using a laparoscope, the polyp was resected via submucosal dissection under direct visualization with a small incision. The polyp was diagnosed as well-differentiated adenocarcinoma in situ and was resected without remnants. PJS is characterized by a high incidence of malignant tumors, and lifelong surveillance for gastrointestinal and extra-gastrointestinal tumors is necessary. The incidence of duodenal cancer is not high among patients with PJS. However, surgery for advanced cancer is highly invasive. It is desirable to detect the tumors at an early stage so that they can be resected via a less invasive treatment method such as endoscopic resection or laparoscopic surgery with an endoscope.

A Rare Clinical Presentation With a Difficult Imaging Diagnosis of an Intra-articular Clear Cell Sarcoma of the Knee.

ABSTRACT: Clear cell sarcoma, a highly aggressive cell sarcoma with melanotic differentiation, typically occurs in the tendon and aponeuroses of the lower extremities and rarely develops in the intra-articular region. Herein, we present an extremely rare case of clear cell sarcoma originating from the intra-articular knee and suspected as benign tumors due to the benign-looking findings on MRI and PET/CT. The image results in our case were completely consistent with a tenosynovial giant cell tumor, resulting in the misdiagnosis. For differential diagnosis, especially malignant melanoma, histopathology, including IHC and FISH, was indispensable.

Case Report: Angiomatoid fibrous histiocytoma in the hand: a rare clinical presentation and diagnostic challenge.

Angiomatoid fibrous histiocytoma (AFH) is a rare tumor of mesenchymal origin occurring in young adults. Based on its clinical course, it is said to have an intermediate potential. We present a case of a 59-year-old woman with AFH in the hand that was difficult to diagnose. A benign soft tissue tumor was suspected on magnetic resonance imaging, and its size and open biopsy suggested nodular fasciitis or inflammatory myofibroblastic tumor. A diagnosis of AFH was eventually made based on the analysis of the resected specimens. The characteristic findings of histopathology and immunohistochemistry in this case were relatively poor, so fluorescence in situ hybridization contributed to making the correct diagnosis. Considering its prognosis, careful follow-up was decided upon without additional surgery. Our case is a challenging one because of its atypical presentation and inconclusive imaging and histopathological findings.

Synovial chondromatosis: Rare involvement of metacarpophalangeal joint and diagnostic challenges in MR imaging.

Synovial chondromatosis (SC) is a rare benign tumor of the cartilaginous tissue that frequently affects large joints intra-articularly. Characteristic imaging findings were reported for the diagnosis of SC. Herein, we report a case of SC of the metacarpophalangeal joint with atypical MRI findings. Considering the clinical presentation, erosion, absence of calcification on X-ray and CT, and low intensity on short tau inversion recovery (STIR), tenosynovial giant cell tumor was the initially diagnosis. However, histopathological findings revealed SC with fibrosis, which was confirmed using Elastica Van Gieson (EVG) staining. In general, low intensity on STIR in SC indicate calcification; however, it can also represent fibrosis in SC. In this case, the diagnosis of SC using MRI was limited highlighting the importance of histopathological findings for an accurate diagnosis of SC.

Indolent Multinodular Synovial Sarcoma of Peripheral Nerves Mimicking Schwannoma: A Case Report and Literature Review.

BACKGROUND/AIM: Most cases of synovial sarcoma (SS) are aggressive and large-sized; only few show indolent behavior, having a small size. Nerves are rare sites of SS occurrence. An atypical case of SS can lead to its misdiagnosis as a benign tumor and delay its treatment. CASE REPORT: Here, we report a case of primary SS of indolent multinodular synovial sarcoma of peripheral nerves. Considering the clinical and imaging findings at the first visit, we suspected a benign tumor and continued careful follow-up. Three years later, marginal resection was performed and SS was suspected. We then performed an additional wide resection using a free flap. Histopathologically, the proximal tumor showed a diffuse proliferation of spindle cells without pleomorphism, whereas the distal tumor showed a similar histology with more hypercellularity. Additional wide-resection specimens showed remnant tumors derived from the peripheral nerve. Immunohistochemistry (IHC) showed positive staining for SS18:SSX and SSX in both tumors and fluorescence in situ hybridization showed positive staining for the SS18 split in both tumors. Finally, SS of the peripheral nerve was diagnosed. Owing to FNCLCC grade 2 tumor and tumor size, adjuvant chemotherapy was not performed. CONCLUSION: In cases of SS or other sarcomas with atypical clinical courses, with imaging findings mimicking benign tumors, we recommend marginal resection along with pathological examination for correct diagnosis.

Primary Synovial Sarcoma of the Bone: A Case Report and Literature Review.

BACKGROUND/AIM: Synovial sarcoma (SS), a spindle cell sarcoma, typically occurs in the soft tissues of the extremities and rarely develops in the bones as a primary tumor. To our knowledge, no case of SS in the metacarpal bone has been reported. CASE REPORT: We report a case of primary SS of the metacarpal bone. Considering the clinical and imaging findings, SS was difficult to diagnose; therefore, we performed an open biopsy. Next, we performed a wide resection following the management guidelines for SS of the soft tissue. Immunohistochemistry (IHC) showed positive staining for SS18:SSX and SSX, and fluorescence in situ hybridization showed positive staining for the SS18 split. Owing to FNCLCC grade 3 tumor and the R1 margin, adjuvant chemotherapy with ifosfamide and doxorubicin was initiated. Finally, SS of the bone was diagnosed. Furthermore, we reviewed a total of 37 published cases of primary bone SS, including our case. Age and sex were almost the same in all cases of bone SS, and the most frequent site was the long bone in the lower extremity. CONCLUSION: IHC for SS18::SSX and SSX antibodies are beneficial for diagnosing general SS and SS of the bone. Moreover, SS of the bone should be considered in the differential diagnosis of spindle cell sarcomas of the bone. Wide resection and chemotherapy are recommended as current treatment strategies, although further studies are required regarding treatment validity.

Case Report: Extraskeletal osteosarcoma with preceding myositis ossificans.

Extraskeletal osteosarcoma (EO) is a soft tissue sarcoma characterized by the production of bone matrix by neoplastic cells. Benign osteoid in EO, leading to a diagnostic dilemma, is rarely encountered. Herein, for the first time, we present a case with cytogenetically confirmed EO combined with or preceding myositis ossificans (MO). A 21-year-old man had a mildly painful swelling in his left knee. Imaging studies demonstrated a 39-mm mass with peripheral mineralization and cystic change on the posterolateral side of the left fibular head. He was clinically suspected of having either MO or a malignancy, such that wide resection was performed. Macroscopically, the mass was grayish to brown. In the cut section, multiple cystic lesions in addition to solid components were noted. Histopathologically, the solid components demonstrated diffuse proliferation of pleomorphic tumor cells with osteoclast-like giant cells. The malignant tumor cells formed osteoid. In the periphery, the mass was benign, showing mature bone tissue and focally non-malignant woven bone with fibroblasts, compatible with zonation. Fluorescence in situ hybridization (FISH) demonstrated split signals of the USP6 gene. These findings suggested EO with preceding MO. Although the pathogenesis remains to be elucidated, the observed USP6 rearrangement might contribute to both the diagnosis of EO with preceding MO and an understanding of the underlying histopathology.

Atypical clinical and radiological presentations of lumbar spinal tuberculosis mimicking a spinal tumor: A case report.

INTRODUCTION: Tuberculosis (TB) is an important infectious disease worldwide. Classical spinal TB has specific radiological findings involving adjacent vertebral bodies with destruction of the intervertebral disc and involvement of paravertebral soft tissues with cold abscess formation. However, a few cases not exhibiting the radiological characteristics of TB spondylitis have been reported. We report a rare case of lumbar spinal TB with atypical clinical and radiological presentations that was difficult to differentiate from a malignant spinal tumor. PATIENT CONCERNS: A 21-year-old man, who had immigrated to Japan from the Philippines 5 years ago, without a significant medical history, presented with back pain lasting 1 month and progression of gait disturbance 2 weeks prior to presentation. DIAGNOSIS: Laboratory tests showed normal blood cell counts and normal value of C-reactive protein levels. Preoperative imaging studies indicated a possible spinal tumor. However, histopathologic findings of the epidural soft tissues at the first surgery led to the diagnosis of spinal mycobacterial infection. The diagnosis of spinal TB was confirmed by a positive culture of Mycobacterium tuberculosis obtained at the second surgery. INTERVENTIONS: Given the progressive nature of neurologic deterioration, instead of needle biopsy, we proceeded with surgical intervention 8 days after admission; simultaneous neural decompression and open biopsy. Histological findings of the excised epidural soft tissues led to the diagnosis of spinal mycobacterial infection. We performed the second surgery involving additional resection of epidural soft tissues for further dural decompression and to obtain specimens for mycobacterial culture. Immediately after the second surgery, the patient commenced combination therapy with anti-tuberculous drugs. OUTCOMES: The patient demonstrated significant recovery of motor function in the lower extremities, and was able to run at 2 months after the second surgery. The epidural granulomas completely disappeared on magnetic resonance imaging 3 months postoperatively. CONCLUSION: Atypical clinical and radiological presentations of spinal TB present a challenge for appropriate diagnosis and early treatment. Even in developed countries where there are very few spinal TB patients, clinicians should be aware that spinal TB is an important differential diagnosis, especially in elderly patients or patients coming from countries with a middle-high prevalence of TB.

Case report: Atypical spindle cell/pleomorphic lipomatous tumor masquerading as a myxoid liposarcoma or intramuscular myxoma.

Atypical spindle cell/pleomorphic lipomatous tumors (ASPLTs) were recently categorized as benign lipomatous tumors. However, accurate and complete preoperative diagnosis of ASPLTs may be difficult. Furthermore, diagnosis based on magnetic resonance imaging (MRI) findings is uncertain because of the varying ratios of the fat component within the tumor. Here, we report a case of ASPLT masquerading as a myxoid tumor. Although MRI findings were consistent with a myxoid liposarcoma, needle biopsy findings suggested a myxoma, and we performed marginal resection. Histopathological findings revealed infiltrating spindle cells with atypia. In addition, immunohistochemistry (IHC) showed positive staining for CD34 and heterogeneous retinoblastoma deficiency, and fluorescence in situ hybridization (FISH) showed no amplification of mouse double minute 2 homolog and no rearrangement of FUS or EWSR1. When MRI and histopathological findings suggest a myxoid tumor, IHC and FISH should be considered and performed for a precise and accurate diagnosis.

Chronic spontaneous epidural hematoma in the lumbar spine with cauda equina syndrome and severe vertebral scalloping mimicking a spinal tumor: a case report.

BACKGROUND: Chronic spinal epidural hematomas (SEHs) are rare clinical entities. SEH with vertebral scalloping is extremely rare, with only a few cases having been reported to date. We report a unique case of spontaneous chronic SEH in the lumbar spine with severe vertebral scalloping mimicking an epidural tumor. CASE PRESENTATION: A 71-year-old man presented with a 2-month history of lumbar pain and a 3-week history of paresthesia and pain in the right lower extremity, hypesthesia in the perineal and perianal regions, and bladder dysfunction. Computed tomography following myelography revealed an epidural mass lesion on the right side that compressed the dural sac and was associated with severe bony scalloping on the posterior wall of the L4 vertebral body. Magnetic resonance imaging (MRI) on T1- and T2-weighted images revealed a space-occupying lesion with heterogeneous intensity, and T1-gadolinium images showed an intralesional heterogeneous enhancement effect. A tumoral lesion in the spinal canal was suspected, based on preoperative imaging; therefore, a total spinal tumor resection was planned. Intraoperative findings revealed that the brownish lesion adhered to the dura and epidural tissues in the spinal canal, and the space-occupying mass in the scalloped cavity of the posterior wall of the L4 vertebra was encapsulated in red-brownish soft tissues. The lesion was totally resected in a piecemeal fashion, and pathological examination revealed a mixture of tissues that contained a relatively new hematoma with hemoglobin, as well as an obsolete hematoma with hemosiderin and amyloid deposits. The mass was diagnosed as a chronic epidural hematoma with recurrent hemorrhage. The postoperative course was uneventful, and the preoperative neurological symptoms immediately improved. CONCLUSIONS: The preoperative diagnosis of chronic SEHs is challenging, as MRI results may not be conclusive, particularly in patients with scalloping of bony structures. Thus, chronic SEHs should be considered as a differential diagnosis in cases of suspected tumoral lesions in the spinal canal. To the best of our knowledge, this is the first reported case of acute exacerbation of chronic SEH with cauda equina syndrome and severe vertebral scalloping.

[A Case of Malignant Peripheral Nerve Sheath Tumor of the Anus Resected by Robot Assisted-APR].

An 81-year-old female visited a local hospital with complaints of anal pain. A tumor was found on the right side of her anus, and the histopathological diagnosis was a non-epithelial malignant tumor. Therefore, the patient was referred to our hospital. Result of imaging inspection revealed that the tumor had invaded the lower rectum, but had not distantly metastasized. Based on the findings of another biopsy, the patient was diagnosed with a malignant peripheral nerve sheath tumor (MPNST). Robot-assisted abdominoperineal resection(D1)was performed, and the lesion was resected without any pathological remnants. During the postoperative period, the patient developed perineal wound infection. Subsequently, the patient was discharged from the hospital on postoperative day 10. At the 6-month postoperative follow-up, no recurrence was noted. Most MPNSTs occur in the limbs, trunk, and neck. MPNST in the primary gastrointestinal tract or in the vicinity of the gastrointestinal tract is relatively rare, and in principle, combined resection of the intestinal tract is required for surgical treatment. Here, we report a case of MPNST that occurred near the anus and infiltrated to the lower rectum and was completely resected by robot-assisted abdominoperineal resection.