Lipomatous hemangiopericytoma of the stomach: A case report and a review of literature

Intermediate metastatic risk lipomatous solitary fibrous tumor of the thigh (previously known as hemangiopericytoma): A rare case report with a literature review

RATIONALE

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor, which can arise at any anatomical location and exhibit a wide variety of histopathological characteristics. Lipomatous solitary fibrous tumor (LSFT) is a rare variant of SFT characterized by hemangiopericytoma-like vascular areas with a varying amount of adipocytic tissue. LSFT can be misdiagnosed with other tumors such as liposarcoma which can lead to unnecessary overtreatment for patients.

PATIENT CONCERNS

A 48-year-old man presented to the hospital clinic with a painless swelling located on the medial area of the upper thigh near the femoral artery, he has not seen any change in its size since he has noticed it a year ago.

DIAGNOSES

Histological examination confirmed LSFT with an intermediate risk of metastasis.

INTERVENTIONS

Three-dimensional imaging technology with intravenous injection of contrast material was made and revealed a mass with well-vascularity supplied from the deep femoral artery. The lesion was excised and showed an intramuscular well-circumscribed encapsulated mass.

OUTCOMES

The pathological findings LSFT with intermediate metastatic risk, and he is scheduled to receive radiotherapy for one and a half months. The majority of SFTs display benign histological characteristics and typically follow a slow clinical progression, leading to a favorable prognosis. To date, fewer than 20 cases of malignant LSFT have been documented. In our case, we utilized a recent tumor classification model that evaluates the metastatic potential of SFTs, and long-term follow-up is necessary because there is a chance of aggressive behavior.

LESSONS

LSFTs are usually found incidentally and often present as painless, movable masses. Even though they mostly follow a benign course, long-term follow-up is essential due to the possibility of turning malignant.

Exploring Solitary Fibrous Tumors at a Tertiary Cancer Center: Clinicopathological and Immunomorphologic Profile

Background Solitary fibrous tumor (SFT) is a distinct fibroblastic tumor that can occur at any anatomical site and can manifest a variety of histopathological features. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its surrogate on immunohistochemistry, STAT6 has also displayed considerable efficacy. Nevertheless, its histologic diversity can result in diagnostic challenges, especially when classic features are not apparent. Methods A retrospective study was conducted at a tertiary cancer centre in North India over 3 years to document the clinicopathologic and immunomorphologic profile of SFTs. Immunohistochemical analysis of BCOR and p53 were gauged additionally and patients were stratified according to Modified Demicco and Salas criteria for risk of metastasis. Results Sixteen patients of SFT were identified, affecting middle-aged men and women equally. Though lung/pleura are known to be involved commonly, SFT affects other sites such as the kidney, brain, buccal mucosa, liver, and penis as well. The majority endured localized disease while a lesser number suffered locoregional/distant spread. Two patients revealed features of a malignant profile. Risk stratification according to the Modified Demicco and Salas criteria evinced comparable results. No discernible relationship however was highlighted between the immunohistochemical expression of BCOR, p53, and any significant SFT parameter. Conclusion Although SFTs are very rare substantially benign mesenchymal neoplasms, pathologists must be conversant with their histological diversity and be vigilant of their malignant attributes. The worth of STAT6 immunohistochemistry for precise diagnosis and long-term studies for delineating clinical behavior cannot be overemphasized.

EUS-Guided Diagnosis of Gastric Subepithelial Lesions, What Is New?

Gastric subepithelial lesions (SELs) are intramural lesions that arise underneath the gastric mucosa. SELs can be benign, but can also be malignant or have malignant potential. Therefore, correct diagnosis is crucial. Endosonography has been established as the diagnostic gold standard. Although the identification of some of these lesions can be carried out immediately, solely based on their echo characteristics, for certain lesions histological examination is necessary. Sometimes histology can be inconclusive, especially for smaller lesions. Therefore, new methods have been developed in recent years to assist decision making, such as contrast enhanced endosonography, EUS elastography, and artificial intelligence systems. In this narrative review we provide a complete overview of the gastric SELs and summarize the new data of the last ten years concerning the diagnostic advances of endosonography on this topic.

The many faces of solitary fibrous tumor; diversity of histological features, differential diagnosis and role of molecular studies and surrogate markers in avoiding misdiagnosis and predicting the behavior

Background

Solitary Fibrous Tumor (SFT) is a distinct soft tissue neoplasm associated with NAB2-STAT6 gene fusion. It can involve a number of anatomic sites and exhibits a wide spectrum of histological features.

Main body

Apart from diversity in morphological features seen even in conventional SFT, two histologic variants (fat-forming and giant cell-rich) are also recognized. In addition, a malignant form and dedifferentiation are well recognized. Owing to diverse histological features and involvement of diverse anatomic locations, SFT can mimic other soft tissue neoplasms of different lineages including schwannoma, spindle cell lipoma, dermatofibrosarcoma protuberans, liposarcoma, gastrointestinal stromal tumor (GIST), malignant peripheral nerve sheath tumor (MPNST), and synovial sarcoma. SFT is classified as an intermediate (rarely metastasizing) tumor according to World Health Organization Classification of Tumors of Soft tissue and Bone, 5th edition. The management and prognosis of SFT differs from its malignant mimics and correct diagnosis is therefore important. Although SFT expresses a distinct immunohistochemical (IHC) profile, the classic histomorphological and IHC profile is not seen in all cases and diagnosis can be challenging. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its IHC surrogate marker signal transducer and activator of transcription 6 (STAT6) has also shown significant sensitivity and specificity. However, few recent studies have reported STAT6 expression in other soft tissue neoplasms.

Conclusion

This review will focus on describing the diversity of histological features of SFT, differential diagnoses and discussing the features helpful in distinguishing SFT from its histological mimics.

Lipomatous hemangiopericytoma of the corpus spongiosum: a case report and review of the literature

BACKGROUND

Hemangiopericytoma (HPC) is an uncommon soft tissue tumor arising from pericytes. The urogenital system is rarely affected.

METHODS

The review of the literature used the PubMed database which was searched up to March 2015.

RESULTS

Herein, we report the first case of lipomatous HPC of the corpus spongiosum in a 37-year-old man in China. The lesion presented as a quickly growing mass. Contrast enhanced CT showed a heterogeneous fatty mass with a multifocal enhancing soft-tissue component. Microscopically, the neoplasm was composed of spindle cells, a mature fat component and collagenous stroma. The mitotic index was low at 1 to 3 mitoses per 10 high-power fields. Immunohistochemically, STAT6, Bcl-2, CD99 and CDK4 were positive; CD34 and SMA were negative. The mature adipocytes were positive for S-100. Ki-67 expression was found in approximately 5% of the tumor cells. Surprisingly, there was a diffuse and strong nuclear expression of MDM2, but, no amplification of MDM2 was demonstrated by FISH. An adequate excision of the tumor was performed.

CONCLUSION

No local recurrence or distant metastases occurred during the 18-month follow-up. In view of the unpredictable biological behavior of this tumor, a long follow-up period is mandatory.

Extrapleural solitary fibrous tumor: A distinct entity from pleural solitary fibrous tumor. An update on clinical, molecular and diagnostic features

Solitary fibrous tumor (SFT) is a mesenchymal neoplasm that was originally described to be localized in the pleura, but thereafter, this has been reported in several anatomic sites. Although the etiology of the neoplasm remains largely unknown, the pathogenesis seems to be related to an NAB2-STAT6 fusion gene due to paracentric inversion on chromosome 12q13. The diagnosis of extrapleural SFT is challenging, owing to its rarity, and requires an integrated approach that includes specific clinical, histological, immunohistochemical, and even molecular findings. Histologically, extrapleural SFT shares morphological features same as those of the pleural SFT because it is characterized by a patternless distribution of both oval- and spindle-shaped cells in a variable collagen stroma. In addition, morphological variants of mixoid, fat-forming, and giant cell-rich tumors are described. A correct diagnosis is mandatory for a proper therapy and management of the patients with extrapleural SFT, as extrapleural SFT is usually more aggressive than pleural form, particularly cases occurring in the mediastinum, retroperitoneum, pelvis, and meninges. Although SFT is usually considered as a clinically indolent neoplasm, the prognosis is substantially unpredictable and only partially related to morphological features. In this context, cellularity, neoplastic borders, cellular atypias, and mitotic activity can show a wide range of variability. We review extrapleural SFT by discussing diagnostic clues, differential diagnosis, recent molecular findings, and prognostic factors.

Lipomatous hemangiopericytoma (adipocytic variant of solitary fibrous tumor) of the parotid gland: A case report and review of the literature

The current study presents the first case of a lipomatous hemangiopericytoma (LHPC) developing in the parotid gland in a 33-year-old male. The patient presented with a 4-year history of a progressively growing painless and fixed mass in the left paratid gland region. The patient underwent radical parotidectomy and was followed-up for 12 months without any evidence of metastasis or recurrence. LHPC, a controversial rare HPC variant, is histologically characterized by a varying admixture of hemangiopericytomatous vasculature and the presence of mature adipocytes. To date, 51 cases of LHPC have been documented in the literature. Although the boundary between HPC and solitary fibrous tumors (SFTs) has become increasingly blurred, neither of these variant growth patterns has previously been recognized in the parotid gland.