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.

[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.

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.

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.

Computed Tomography Imaging Findings for Predicting Histological Subtypes and Clinical Outcomes in Patients With Head and Neck Nodal Involvement of Diffuse Large B-Cell Lymphoma and Follicular Lymphoma.

OBJECTIVE: This study aimed to assess computed tomography (CT) imaging findings for predicting the histological subtypes and clinical outcomes in patients with head and neck nodal involvement of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). METHODS: This retrospective study included 64 patients with histologically confirmed head and neck nodal lymphoma (43 with DLBCL and 21 with FL) who underwent pretreatment CT examinations. The CT imaging findings were retrospectively assessed and compared according to the 2 pathologies and their clinical outcomes. RESULTS: Multiplicity (86% vs 57%, P < 0.05), necrosis (44% vs 5%, P < 0.01), ill-demarcated margin (33% vs 0%, P < 0.01), and surrounding fat stranding (56% vs 14%, P < 0.01) were significantly more frequent in DLBCLs than in FLs. Multivariate logistic regression analysis revealed that necrosis was a significant factor for predicting the diagnosis of DLBCL (P < 0.01). Multiplicity (100% vs 67%, P < 0.01), bilaterality (44% vs 13%, P < 0.05), and surrounding fat stranding (69% vs 28%, P < 0.01) were significantly more frequent in the poor outcome group than in the good outcome group. Multivariate logistic regression analysis revealed that bilaterality and surrounding fat stranding were significant factors for predicting poor outcomes (P < 0.05). CONCLUSIONS: In patients with head and neck nodal lymphoma, necrosis was useful for predicting the diagnosis of DLBCL, whereas bilaterality and surrounding fat stranding were useful for predicting poor outcomes.

Magnetic Resonance Imaging Characteristics of Poroma and Porocarcinoma.

PURPOSE: The purpose of this study was to evaluate magnetic resonance (MR) imaging findings of poroma and porocarcinoma. METHODS: Six patients (3 male, 3 female; age range, 40-84 years; mean age, 61 years) with histologically confirmed skin appendage tumors with apocrine and eccrine differentiation (2 poromas and 4 porocarcinomas) were enrolled. All patients underwent preoperative MR imaging and the MR images were retrospectively reviewed. RESULTS: The configurations were classified as pedunculated solid in 5 lesions and subcutaneous cystic with mural nodules in 1. Well-demarcated deep tumor margins and smooth skin surfaces were observed in all 6 lesions, and peritumoral fat stranding was observed in 2. In all 5 pedunculated solid lesions, T2-hyperintense foci, T1 hyperintensity, and homogeneous solid components were observed within the lesions. CONCLUSIONS: Poroma and porocarcinoma usually exhibited pedunculated solid homogeneous lesion. Intratumoral T2-hyperintense foci and T1 hyperintensity were observed in pedunculated solid lesions.

Melorheostosis with recurrent soft-tissue components: a histologically confirmed case.

Melorheostosis is a very rare disorder characterized by irregular cortical thickening seen on radiographs. In this paper, we present a case of melorheostosis with microscopically confirmed soft-tissue components. The patient was a 51-year-old man who complained of severe pain in the lateral aspect of his right knee. The excision of an ossified soft-tissue lesion relieved intractable pain that had lasted 20 years. Microscopically, the cortex of the affected fibula was composed of thick compact bone and the soft-tissue component consisted of dense compact bone without endochondral ossification. The presence of soft-tissue osseous nodules around the joints is one of the specific conditions for melorheostosis and should be differentiated from synovial chondromatosis. The ossified soft-tissue lesion in our patient is to our knowledge the first reported case of the histologically confirmed soft-tissue component of melorheostosis, which differs from that of synovial chondromatosis.

Gastric mucosal status susceptible to lanthanum deposition in patients treated with dialysis and lanthanum carbonate.

Lanthanum carbonate is a popular chemical which is administered for patients with end-stage kidney disease to reduce the absorption of phosphate, and lanthanum deposition in the gastroduodenal mucosa has recently been reported. The aim of this study was to assess whether any histologic changes of the gastric mucosa are related to the deposition of lanthanum. Twenty-four patients who revealed the histology of lanthanum deposition on gastroduodenal biopsy between 2011 and 2014 were included in the study, and their clinical records and gastroduodenal biopsies obtained from 2011 to 2015 were reviewed, adding the review of gastroduodenal biopsies before 2011 if possible. Analysis of the deposited materials by scanning electron microscopy-energy dispersive x-ray spectroscopy was performed for a representative gastric biopsy. All patients were diagnosed as having renal insufficiency due to chronic kidney disease and treated with dialysis for more than 5 years, with confirmation of lanthanum carbonate use for 22 patients. Of 121 gastric biopsies and 10 duodenal ones between 2011 and 2015, 86 gastric biopsies (71.1%) and 3 duodenal biopsies (30%), respectively, revealed histology consistent with lanthanum deposition, which was confirmed by scanning electron microscopy-energy dispersive x-ray spectroscopy analysis for a representative case. The deposition tended to occur in the gastric mucosa with regenerative change, intestinal metaplasia, or foveolar hyperplasia (P<.05). Such mucosal changes were observed in about half of the gastric biopsy samples obtained prior to 2010, in which no lanthanum deposition was identified irrespective of the gastric mucosal status. Although direct association between lanthanum deposition and clinical symptoms is not clear, the evaluation of the gastric mucosal status (prior to administration) seems to be important to predict lanthanum deposition when lanthanum carbonate is administered for patients with chronic kidney disease treated with dialysis.

A lethal intracranial Rosai-Dorfman disease of the brainstem diagnosed at autopsy.

Rosai-Dorfman disease (RDD) is a benign histiocytic proliferative disorder characterized by the accumulation of histiocytes in lymph nodes and various other organs. RDD seldom involves the central nervous system, and cases of purely intracranial RDD are particularly rare. We report a case of purely intracranial RDD involving the brainstem that was diagnosed at autopsy. A 68-year-old woman visited our hospital because of visual disturbances and loss of energy. Magnetic resonance imaging revealed an obscure mass in the brainstem. Despite exhaustive work-ups, the etiology of the intracranial mass remained unclear. The patient died of respiratory depression, and an autopsy was performed for pathological investigation. Macroscopically, a pink pale mass 2.5 cm in diameter was found in the brainstem, with no attachment to the dura. Histologically, it was composed of histiocytic cells with incorporation of small lymphocytes (emperipolesis). Immunohistochemical staining revealed that the cells were positive for CD68 and S100 and negative for CD1a, consistent with a diagnosis of RDD. Purely intracranial RDD is extremely rare and considered benign. To date, nine cases (including ours) have been reported. To our knowledge, this is the first case of intracranial RDD with autopsy. Although generally considered benign, RDD involving the brainstem might be lethal.

Distinct patterns of peritumoral histological findings in subtypes of intraductal papillary mucinous neoplasms of the pancreas.

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are primary pancreatic neoplasms that can act as precursors to invasive adenocarcinoma of the pancreas. The peritumoral stroma has been increasingly recognized to play an important role in many types of tumors. Therefore, to investigate the clinicopathological significance of the peritumoral stroma in IPMNs, we examined the histological features of the peritumoral stroma in each subtype and histological grade of IPMNs. Eighty-two patients with IPMN, who underwent surgical resection, were reviewed clinicopathologically. Intraductal papillary mucinous neoplasms (86 lesions in total) were histologically subclassified into gastric (n = 51), intestinal (n = 22), pancreatobiliary (n = 11), and oncocytic (n = 2) subtypes. Peritumoral histological features between the gastric and intestinal subtypes were evaluated by each histological grade. The results showed that subepithelial edema and inflammatory cell infiltration were more commonly observed in the gastric subtype (74% and 79%, respectively) than in the intestinal subtype (12% and 25%, respectively) of low-grade IPMNs. On the other hand, mucus lakes were more commonly observed in the intestinal subtype (100%) than in the gastric subtype (0%) of high-grade IPMNs. In addition, pancreatobiliary subtype IPMNs tended to exhibit acute inflammation such as neutrophil predominance. This study showed that peritumoral histological features differed among subtypes of IPMNs from low-grade tumors. These differences suggest the possibility that each subtype of IPMNs has a distinct mechanism from an early stage of tumor progression, which is reflected in the properties of the peritumoral stroma.

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.

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 [...].

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.

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.

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: 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.

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.