Rare case of paratesticular solitary fibrous tumour (lipomatous hemangiopericytoma)

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.

Solitary fibrous tumor developing in the right retroperitoneal space

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor that is quite aggressive and prone to recurrence and metastasis. Most SFTs are benign, but the identification of the histological features that define the dedifferentiation of SFTs can predict the aggressiveness of the tumor and the presence of a reserved prognosis. We present a rare case of conventional SFTs with features of malignancy and highlight the diagnostic and therapeutic difficulties related to this case. Computed tomography aspect suggested a possible gastrointestinal stromal tumor. Surgical intervention was performed through median laparotomy and a tumor of approximately 15∕12 cm was found, developed from the level of the right retroperitoneal space, and pushing anteriorly the ascending colon, cecum, and terminal ileum. The immunohistochemical aspect correlated with the histopathological one suggests a SFT most likely malignant. In conclusion, the early diagnosis of SFTs is essential in establishing an appropriate treatment. Immunohistochemistry is indispensable in establishing the diagnosis of SFTs.

Imaging in paratesticular lesions

A 23-year-old male presented with complaints of gradually increasing swelling of the left hemiscrotum. Preliminary ultrasound scan revealed a heterogeneous, predominantly solid lesion showing raised internal vascularity with few cystic areas in the paratesticular region, towards the midline with both testes seen separately from the lesion. To rule out presence of locoregional or distant metastases, a CT scan was done which revealed a well-defined, intrascotal, extratesticular, heterogeneous, moderately enhancing mass lesion with cystic areas in the scrotal sac with no significant lymphadenopathy or obvious distant metastasis. Subsequent MRI done for surgical planning revealed a heterogeneous signal intensity lesion with cystic areas and areas of haemorrhage with focal loss of fat planes with the left corpora cavernosa at the root of the penis. The patient underwent an inguinoscrotal exploration with excision of the left paratesticular mass. Final histopathology suggested an undifferentiated high grade pleomorphic sarcoma. Paratesticular tumours while rare are an important cause of scrotal swelling. Exact histological identification of tumour subtype is not possible based on imaging but preoperative multi-modality imaging has an important role in identifying tissue of origin, differentiating benign from malignant lesions, surgical planning and assessing the need for adjuvant CT/RT.

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.

Solitary fibrous tumor of the scrotum: a case report and review of the literature

BACKGROUND

Solitary fibrous tumor (SFT) is a rare soft tissue tumor originally reported in the pleura. Although it has been reported in various extra-pleural sites, the occurrence of SFT in the scrotum is extremely rare. Herein, we present a 48-year-old man who had scrotal SFT. There are very few reported cases of genitourinary SFTs, this is only the fifth report of SFT of the scrotum in the English medical literature.

CASE PRESENTATION

In this study, we report on a 48-year-old man who presented with a 5 × 8 cm scrotal mass between his testes. Physical examination revealed a 4.7 × 8.5 cm lobulated tumor mass located between his testicles. Surgical excision of the tumor with scrotal approach was done and pathology reported a SFT. The patient was alive without tumor recurrence or distant metastasis during ongoing follow-up for 9 months post-operatively..

CONCLUSION

Scrotal SFTs are very rare and only five cases have been reported in English literature to date. Treatment often involves surgical resection, and a definite diagnosis is made with the help of immunohistochemistry. The current general consensus for the management of SFTs is long-term follow-up after surgical excision of the tumor.

Florid Proliferation of Hyalinized Vessels in a Spermatic Cord STAT6 Positive Solitary Fibrous Tumor and Its Potential Clinical Implications

A solitary fibrous tumor (SFT) arising in the paratesticular region is a rare event. Typically most SFTs present as a lung mass and have a characteristic microscopic appearance. Although uncommon, SFTs may present at just about any anatomical site. Here we present a case of a SFT arising along the right spermatic cord, with histologic features mimicking a cellular angiofibroma. We describe the diagnostic immunohistochemical markers useful for arriving at its diagnosis. We also summarize our current understanding of the structural and molecular features that make up SFTs and discuss how these features may help us better understand the pathophysiology of pluripotent mesenchymal stem cell differentiation.

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.

Histopathological Spectrum of Tumor and Tumor-like Lesions of the Paratestis in a Tertiary Care Hospital

OBJECTIVES

Tumors and tumor-like lesions (TLL) of the paratesticular region are rare. Very few studies depicting the spectrum of lesions of this location are available in the literature. Malignant neoplasms arising in the paratesticular region represent only 7.0% of malignant tumors presenting as a scrotal mass. TLL and benign tumors are of great interest, because of their topography they can simulate a neoplasm in the paratesticular structures. We sought to study the incidence, nature, pattern, clinical, immune, and histopathological characteristics of tumors and TLL of the paratestis.

METHODS

In this six-year study, records of the cases were reviewed and the histopathology slides were reassessed. Blocks were retrieved and stained immunohistochemically for relevant markers.

RESULTS

A total of 47 cases of tumor and TLL of the paratestis were diagnosed over a six-year period. The patients ranged from one to 76 years old and most presented with a scrotal mass. Of these, seven (14.9%) were benign. Lipoma was the most common benign tumor. One case each of adenomatoid tumor, scrotal hemangioma, solitary fibrous tumor, and papillary cyst adenoma were reported. The TLL (70.2%) comprised of 17 cases of epididymal cyst, seven cases of tuberculous epididymitis, four cases of filarial epididymitis, two cases each of non-specific granulomatous epididymitis and fibromatous periorchitis, and one case of mesothelial cyst. Seven malignant tumors (14.9%) were diagnosed all of which were sarcomas. All seven were primary to the paratesticular region. The most common malignant tumor was embryonal rhabdomyosarcoma. One case each of malignant mesothelioma, malignant fibrous histiocytoma, atypical lipomatous tumor/well-differentiated liposarcoma, and myxoid liposarcoma were identified.

CONCLUSION

Neoplasms of the paratesticular region affect patients of all ages, with potentially life-threatening sequelae. Awareness of the entire spectrum and meticulous histopathological examination and immunohistochemical studies are of prime importance in the diagnosis of the various lesions as these influence the mode of therapy and subsequent prognosis of the patient.

Paratesticular solitary fibrous tumor: a case report and review of literature

Solitary fibrous tumor (SFT) is a rare spindle cell neoplasm that usually arising from the pleura, but has been reported in diverse extrapleural sites. Urogenital localization is rare, and only several cases of paratesticular SFT have been reported. In the present report, we present the case of a 61-year-old male suffering from a paratesticular SFT. A surgical excision of the lesion was performed. The tumor was well circumscribed and consisted of a mixture of bland spindle cells and dense collagen bands. Immunohistochemical studies showed positive reactivity for CD34, CD99 and vimentin, but stained negative for CD117, S100, SMA, HMB45, Desmin and CD68. All these clinicopathologic features are suggestive of the diagnosis of paratesticular SFT.

Paratesticular sarcomas: two cases with different evolutions

Paratesticular sarcomas are rare and account for less than 1% of all adult sarcomas. Intrascrotal tumours can be testicular or paratesticular, paratesticular tumours being rarer (7-10%). Only 30% of paratesticular tumours are malignant and 90% of these are sarcomas. Histological subtypes include leiomyosarcoma, rhabdomyosarcoma, liposarcoma and undifferentiated high-grade pleomorphic sarcoma. Recurrence is frequent in this type of tumour and can occur years from initial diagnosis. These reports show two cases of paratesticular sarcoma with very distinct evolutions. The first case concerns a patient who presented with low-grade leiomyosarcoma with two local recurrences treated with surgery, and distance recurrence with cutaneous, subcutaneous, pulmonary and hepatic metastasis 30 years after surgery of the primary tumour. The second case reports of a patient who presented with high-grade myxoid liposarcoma with local and distance recurrence 3 years after surgery of the primary tumour, which progressed after chemotherapy; the patient died 7 months after diagnosis of recurrence.

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.