Large Soft Tissue Mass Research Articles

SUN-490 Mass Cord Compression: Metastasis of Insular Thyroid Cancer

Intro: Insular thyroid cancer is a rare and complex form of thyroid cancer, often referred to as poorly differentiated carcinoma. The exact incidence of insular thyroid cancers is difficult to assess due to controversial classification of this thyroid cancer over the years. It is termed poorly differentiated as it falls between the well-differentiated and undifferentiated carcinomas both morphologically and biologically[1]. Case: A 41 year old Hispanic female, with a history of prolactinoma and hyperparathyroidism, presented to the hospital with 10 days of progressive lower extremity weakness and paresthesias from T4 downwards, inability to bear weight, and no bowel movement for 12 days. MRI revealed a large thoracic soft tissue mass (7x4x4cm) centered in the posterior and medial aspect of the chest wall at T4-T5 with involvement of the spinal cord and vertebral bodies. She was also found to have a right sided thyroid mass (4.5x5x4 cm) with tracheal deviation-HerThyoid function test, were normal Intact PTH was 261, Thyroglobulin over 300, and Thyroid Antibodies were negative. Patient underwent T3-T6 laminectomy, T2-T7 fusion, and T4-T5 tumor resection, which was subtotal due to vascularity. Second procedure included a right thoracotomy, chest wall resection of ribs 4 and 5 with full resection of paraspinal mass, total thyroidectomy, parathyroidectomy with central cervical lymphadenectomy. Pathology results of paraspinal mass showed insular thyroid carcinoma.Post operatively, the patient reported improvement of sensation and strength in lower extremities. Genetic testing for MEN syndrome was negative. Discussion: Insular thyroid carcinoma, also referred to as poorly differentiated carcinoma is a rare form of thyroid cancer. Insular carcinoma was characterized by to include the following complex histologic features, “formation of solid clusters (insulae) of tumor cells containing a variable number of small follicles; variable but consistently present mitotic activity, capsular and blood vessel invasion; and frequent necrotic foci, sometimes leading to formation of peritheliomatous patterns”[1]. The cells originate from follicular epithelium and possess the potential to concentrate radioiodine[2]. Unlike anaplastic carcinoma of the thyroid, p53 and p21 staining was negative in insular carcinomas[3]. Thyroglobulin staining is generally positive[4]. Distant metastasis occurs in about 31% of patients with insular thyroid carcinoma[5]. In cases of distant metastasis, treatment with thyroidectomy and radioiodine therapy were shown to independently improve survival[5].The Constellation of Insular thyroid cancer, hyperparathyroidism and Prolactinoma, has not been reported before.

Treatment of abdominal granuloma and hypercalcaemia caused by Cladophialophora bantiana with combination antifungal chemotherapy and hyperbaric oxygen therapy in a dog

A 5-year-old intact male Boxer was evaluated for a 4-month history of ventral abdominal mass with fistulous tracts. Thoracic and abdominal CT revealed a large soft-tissue mass in the rectus...

NUT Carcinoma Resulting in SVC Syndrome

NUT (nuclear protein in testis) carcinoma is a poorly differentiated aggressive subtype of squamous cell carcinoma. NUT carcinoma is characterized by genetic rearrangements involving the NUT gene, resulting in the formation of oncogenic fusion proteins, most commonly NUT-BRD4. Originally described as a thymic carcinoma with NUT gene rearrangement in children and young adults, NUT carcinoma has been shown to occur in adults in a variety of locations. It is typically seen as an aggressive large soft tissue mass infiltrating adjacent structures. Because of the aggressive nature of NUT carcinoma, patients typically present in late stages of the disease and rapidly succumb to the disease. There are no pathognomonic, radiologic, or histopathologic features, and therefore NUT carcinoma is diagnosed via molecular assay, including a commercially available immunohistochemical assay. Additional molecular assays can be performed to demonstrate NUTM1 rearrangement and also to identify the oncogenic fusion protein. With more recent widespread availability of these assays, the reported incidence of NUT carcinoma is expected to increase. Prognosis remains poor for those diagnosed with NUT carcinoma, as there is no proven effective treatment. Recent research into the oncogenic fusion proteins driven by NUT rearrangement and clinical trials with targeted inhibitors offer hope for future therapy.

ECTOPIC NON FUNCTIONAL PITUITARY ADENOMA – A CASE REPORT

Ectopic pituitary adenoma comprises 1–2% of all pituitary adenomas with a slight female predominance. Cases have been reported in the sphenoid sinus, cavernous sinus, parasellar region, nasal cavity, clivus, nasopharynx, and third ventricle. Here, we report the case of a 48-year-old female patient who presented with a 2 years history of nasal obstruction, epistaxis, and headache. The patient underwent necessary hematological, biochemical, and radiological investigations. Magnetic resonance imaging brain with angiography study showed a large soft-tissue mass in nasopharynx eroding the clivus and extending to involve bilateral sphenoid sinuses and parasellar region. The airway was also compromised. The pituitary gland appeared normal. All hematological and biochemical investigations were within normal limits. An endoscopic biopsy was also done. Tissue was submitted for histopathological examination and a diagnosis of pituitary adenoma was given. The patient had uneventful post-operative recovery and regularly came for follow-up.

P1250 Thymoma invading the right atrium - multimodality imaging and its importance for managing and therapeutics

Abstract Introduction Thymoma is the most common primary neoplasm of the anterior mediastinum. Most invasive thymomas are limited to the pericardium. Only few cases of transcaval extension with intracardiac involvement have been reported. Case report We present the case of a 15-year-old boy with previous history of infectious cerebelitis without neurologic sequelae. He presented with interscapular pain for 6 weeks (not improving with symptomatic therapy) and fever for 3 days. On admission, chest radiograph exhibited an opacification in the right hilum (Figure A). He was discharged with antibiotic prescription for presumptive pneumonia. Due to persistence of complaints he was revaluated after 5 days. Signs of superior vena cava (SVC) syndrome were noted. A computerized tomography showed a large soft tissue mass of the anterior mediastinum, in right antero-lateral topography, measuring 12.5x10x9.5 cm with central calcification and extension to the right lung (Figure B). Transthoracic and transoesophageal echocardiography showed an anterior mass compressing the pulmonary artery branch (PA) and SVC with marginal invasion of the right atrium (RA) (Figure C and D). Cardiac MRI confirmed a large mass of the anterior mediastinum with extension and invasion of the right superior lobe, invasion of the superior vena cava with extension into the RA (Figure E). Transthoracic core-needle biopsy was performed and histopathological diagnosis confirmed an invasive thymoma. The case was discussed at joint cardiothoracic surgery and oncology multidisciplinary meeting and it was agreed to neoadjuvant chemotherapy regimen followed by surgery. Intraoperatively, a large tumor invading the SVC and proximal RA was found, in accordance with the echocardiographic and MRI findings. Due to unforeseen metastatic implants on the adventitia of the main PA and ascending aorta, resection of the tumor was not performed. Palliative decompression of the venous system was performed with interposition of a ringed vascular prosthesis between the left brachiocephalic vein and the right atrial appendage. (Figure F). The patient received postoperative radiotherapy and is asymptomatic without signs of SVC syndrome for 3 months. Discussion and conclusion This report illustrates a rare case of an invasive thymoma with extension to cardiac structures. Multimodality imaging for quality decision-making was imperative in the management and for surgical planning of this case. Transthoracic and transoesophageal echocardiography remain the exams of choice for the diagnosis of intracardiac disease. As demonstrated, a high index of suspicion is needed because clinical symptoms are unspecific and late diagnosis of potentially resectable tumors are associated with a poor prognosis. Abstract P1250 Figure. Multimodality imaging

PAPILLARY CYSTADENOCARCINOMA: A CASE REPORT

Papillary cystadenocarcinoma (PCC) is a rare malignant tumor of the salivary glands featured by cysts and papillary endocystic projections. The differential diagnosis includes cystadenoma, papillary-cystic variant of acinic cell carcinoma polymorphous low-grade adenocarcinoma (PLGA), salivary duct carcinoma, and adenoid cystic carcinoma (ACC). Nuclear pleomorphism, mitosis, and infiltrative growth pattern affirm the malignancy of PCC. A 66-year-old man presented with a swelling in the upper alveolar ridge and hard palate. Intraorally, an exophytic, friable and ulcerated lesion was observed. Computed tomography scan showed a large soft tissue mass destroying the left maxilla. An incisional biopsy was performed. Based on the histopathologic features of papillary projections extending into the cystic lumen, the diagnosis of PCC was confirmed. The patient was referred to an oncology center where chemotherapy and radiotherapy were chosen as the appropriate treatment. Currently, no signs of recurrence were detected after 2 years of clinical follow-up. Papillary cystadenocarcinoma (PCC) is a rare malignant tumor of the salivary glands featured by cysts and papillary endocystic projections. The differential diagnosis includes cystadenoma, papillary-cystic variant of acinic cell carcinoma polymorphous low-grade adenocarcinoma (PLGA), salivary duct carcinoma, and adenoid cystic carcinoma (ACC). Nuclear pleomorphism, mitosis, and infiltrative growth pattern affirm the malignancy of PCC. A 66-year-old man presented with a swelling in the upper alveolar ridge and hard palate. Intraorally, an exophytic, friable and ulcerated lesion was observed. Computed tomography scan showed a large soft tissue mass destroying the left maxilla. An incisional biopsy was performed. Based on the histopathologic features of papillary projections extending into the cystic lumen, the diagnosis of PCC was confirmed. The patient was referred to an oncology center where chemotherapy and radiotherapy were chosen as the appropriate treatment. Currently, no signs of recurrence were detected after 2 years of clinical follow-up.

PO 18120 - Eccrine poroma associated with a poroid hidradenoma in a large single lesion over the foot

Introduction: Eccrine poroma (EP) and poroid hidradenoma (PH) are rare benign neoplasms derived from eccrine sweat glands of the epithelium. Both are variants of poroid neoplasms and rarely become malignant. This report describes the clinical presentation, radiographic and pathological features as well as the treatment of a rare association of EP and PH in a large single lesion over the foot. Case Report: We present a 55-year-old male patient with a large soft tissue mass over the midfoot (approximately 7 cm in length and 4 cm width). It started as a hyperchromic black spot on the skin and has slowly grown over the last eight years. One year prior, pain increased significantly. There was no history of trauma, infection or other tumor in this part of the foot. In the physical exam, the tumor had well-defined edges, fibroelastic consistency and was not adherent to the surrounding soft tissue. Preoperative planning included radiographic exams: X-ray and magnetic resonance imaging (MRI). On the MRI, the tumor showed a low signal intensity on T1-weighted images, with heterogeneous high and low signal intensities on T2-weighted images. Strong contrast enhancement was observed after intravenous gadolinium administration in the base portion. The peripheral portion showed a low signal intensity without enhancement. We decided on total resection, and the procedure was performed in January of 2017. The surgical approach was a longitudinal dorsomedial incision over the first ray starting from the ankle joint to the distal third of the first metatarsal. The entire tumor was excised with clean margins and sent for anatomopathological analysis and histopathological examination. Histopathologic examination showed that the tumor was a poroid neoplasm consisting of both dermis (poroid hidradenoma) and epidermis (eccrine poroma) components. There were no features of malignancy. After 20 months of surgery, patient remains asymptomatic with no signs of recurrence of the tumor. Conclusion: Skin tumors must be born in mind in the differential diagnosis of a chronic mass in the foot. Surgical treatment for this type of tumor is curative and prevents recurrence and malignant change.

Sinonasal desmoplastic small round cell tumor: a case report and review of the literature

BackgroundDesmoplastic small round cell tumor (DSRCT) is a rare malignancy with poor prognosis that generally involves the peritoneum. Its diagnosis can be achieved only by immunohistochemistry and cytogenetic studies.Case presentationIn the current report, a 55-year-old female was admitted in our hospital for evaluation of right eye epiphora and right nasal intermittent bleeding. Imaging examination revealed a large soft tissue mass in the right nasal cavity and ethmoid sinus. After an explorative surgery, the pathological findings confirmed the presentation of sinonasal DSRCT. Immunohistochemistry and cytogenetic studies confirmed the diagnosis of DSRCT in this patient. Surgical resection, chemotherapy, and radiotherapy was performed, and she died 2 months after operation.ConclusionThis reported case draws attention to the importance of novel treatments and including DSRCT in the differential diagnosis of sinonasal tumors.

The role of 18F-FDG-PET/CT in evaluating retroperitoneal masses -Keeping your eye on the ball!

BackgroundTesticular germ cell tumour is the commonest malignancy affecting males aged between 15 and 35, with an increased relative risk amongst those with a history of cryptorchidism. In patients presenting with locoregional metastatic disease, retroperitoneal and pelvic soft tissue masses are common findings on ultrasound and computed tomography, which has several differential diagnoses within this demographic cohort. On staging 18F-FDG-PET/CT, understanding the typical testicular lymphatic drainage pathway facilitates prompt recognition of the pathognomonic constellation of unilateral absence of testicular scrotal activity, and FDG-avid nodal masses along the drainage pathway. We describe the cases of three young males presenting with abdominopelvic masses, in whom FDG-PET/CT was helpful in formulating a unifying diagnosis of metastatic seminoma, retrospectively corroborated by a history of testicular maldescent.Case presentationsIn all three cases, the patients were males aged in their 30s and 40s who were brought to medical attention for back and lower abdominal pain of varying duration. Initial imaging evaluation with computed tomography and/or ultrasound revealed large abdominopelvic soft tissue masses, with lymphoproliferative disorders or soft tissue sarcomas being high on the list of differential diagnoses.As such, they were referred for staging FDG-PET/CT, all of whom demonstrated the pathognomonic constellation of, 1) unilateral absence of scrotal testicular activity, and 2) FDG-avid nodal masses along the typical testicular lymphatic drainage pathway. These characteristic patterns were corroborated by a targeted clinical history and examination which revealed a history of cryptorchidism, and elevated β-hCG in two of three patients. All were subsequently confirmed as metastatic seminoma on biopsy and open resection.ConclusionThese cases highlight the importance of clinical history and examination for the clinician, as well as a sound knowledge of the typical testicular lymphatic drainage pathway for the PET physician, which would assist with prompt recognition of the characteristic imaging patterns on FDG-PET/CT. It further anecdotally supports the utility of FDG-PET/CT in evaluating undiagnosed abdominopelvic masses, as well as a potential role in the initial staging of germ cell tumours in appropriately selected patients.

Gastrointestinal stromal tumor at an unusual site with an unusual presentation

Gastrointestinal tumors (GIST) are malignant and rare forms of soft tissue sarcoma arising from interstitial cells of Cajal. With most common site of origin being stomach, Jejunal GIST accounts for 0.1–3% of all GIST. Due to non specific signs and symptoms diagnosis is often delayed and patient mostly presents in advanced stage. 50 year old female presented with decreased appetite from 5 months and lump in upper abdomen from 3 months associated with dull abdominal pain from 15 days. CECT abdomen showed a large soft tissue mass in left lumbar region. Exploratory laparotomy showed a highly vascular mass of size 12x10x8 cm abutting mesentery of transverse colon lodged between middle colic artery and superior mesenteric artery. Resection of mass with a segment of jejunum was done. Histopathological examination showed spindle cell tumor with high mitotic index with CD 117+. Adjuvant chemotherapy was given and patient is currently asymptomatic after 9 months of postoperative follow up. Spectrum of clinical presentation is broad so a preoperative diagnosis is difficult. GIST primarily presenting as an abdominal lump is rare and only 25 cases have been reported so far. Surgery is the primary mode of treatment but imatinib has transformed the treatment. Newer drugs are under phase II trials and hopefully will change the course of management in near future.

Fatal phaeohyphomycosis due to Exophiala sp. infection in a free-living common toad Bufo bufo.

A wild adult female common toad Bufo bufo found dead in Scotland in September 2016 was observed to have hepatomegaly, a large soft tissue mass in the coelomic cavity (2.7 g, 3.5 × 2.3 × 1.8 cm) and numerous dark-red papules (1-2 mm diameter) in the skin and subjacent tissue over the back and dorsal aspects of the limbs. Histopathological examination identified marked hepatitis and coelomitis associated with pigmented fungal hyphae, which are results consistent with a diagnosis of phaeohyphomycosis. Sequencing of the internal transcribed spacer region and the D1-D2 region of the large subunit of the ribosomal RNA gene from affected liver tissue identified the presence of Exophiala (Chaetothyriales) sp., a black yeast previously identified as a cause of amphibian phaeohyphomycosis. To our knowledge, this is the first published report of Exophiala sp. in a wild or captive amphibian in Europe and the first description of phaeohyphomycosis affecting a free-living amphibian in Great Britain. Exophiala spp. are saprobes and opportunistic pathogens. It has been postulated that phaeohyphomycosis is a disease of immunocompromised amphibians; however, we found no evidence of significant concurrent infection or generalised debility in this common toad. Phaeohyphomycosis appears to be a sporadic cause of mortality in amphibians, and this report adds to the growing list of pathogens known to affect wild amphibians in Europe.

Imaging findings of metallic implants associated lymphoma

Purpose Chronic inflammatory condition such as metallic implants insertion state has relevance to develop diffuse large B-cell lymphoma (DLBCL). The purpose of this study is to introduce the imaging features of the metallic implants associated lymphoma. Materials and Methods In 2016 September, a 58 years-old male underwent high tibial osteotomy at right leg after took a knee magnetic resonance image (MRI). After 15 months later, he underwent hardware removal operation. 2 weeks later after operation, he complained right leg pain and swelling. He was hospitalized and radiologic studies including ultrasound (US) and MRI were performed. Soft tissue mass in right popliteal fossa was seen and US-guided biopsy was done to confirm the mass. Results MRI which was taken after hardware removal, showed iso to slightly low signal intensity on T1 weighted image(WI), high signal intensity on T2WI with diffuse marrow involvement and heterogeneous patchy enhancement in right proximal tibia. Also extensive extraosseous soft tissue component was seen, with relatively preserved trabecular pattern in proximal tibia. This intraosseous and extraosseous lesions were not seen in previous MRI which taken before high tibial osteotomy. On US image, it was showed heterogeneous hypoechoic and hypervascular lesion in popliteal fossa of left lower leg. US guided biopsy was done on extraosseous soft tissue mass in left popliteal fossa. It was histologically confirmed as DLBCL. Conclusion Hypoechoic and hypervascular disproportionally large extraosseous soft tissue mass without prominent bone destruction is preferential finding of bone lymphoma. Lymphoma should be considered above all, when these findings were seen in patient who has metallic implant.

Non-rhabdomyosarcoma soft tissue sarcoma in a neonate, a rare and aggressive disease: case report

Neonatal soft tissue sarcomas are a rare group of tumors. The behavior and aggressiveness of neonatal STS is variable. Surgical excision has been noted to be most important factor affecting outcome. However, when non-mutilating surgery is not possible, or resection is incomplete, chemotherapy and radiotherapy have been tried with variable success. We encountered a case of a neonate having large soft tissue mass at anterior abdominal wall. Biopsy and immunohistochemistry confirmed it as undifferentiated soft tissue sarcoma. Surgical excision was incomplete with margin positivity. His disease showed recurrence in short duration of time and despite adjuvant chemotherapy, progression was noted. The child abandoned the treatment and died within 3 months of life.

AB019. LA04. Approach to the prevascular mass

: A wide variety of lesions can present as a localized tumor or mass in the mediastinum. The radiological evaluation of these patients begins with chest radiograph and is followed by CT or MRI. CT and MR imaging allow visualization of the exact location of the lesions and, in some cases, identification of the structures from which they arise. The International Thymic Malignancy Interest Group (ITMIG) has introduced a new definition of mediastinal compartments to be used with cross-sectional imaging and adopted as a new standard. This clinical classification defines 3-compartment model of prevascular (anterior), a visceral (middle), and a paravertebral (posterior) compartment, with anatomic boundaries defined clearly by computed tomography. The most common masses in the prevascular compartment include thymic abnormalities (cysts, hyperplasia, thymoma, thymic carcinoma, and neuroendocrine tumors), germ cell neoplasms, lymphoma; metastatic lymphadenopathy, and intrathoracic goiter. Thymoma is classified into non-invasive and invasive thymoma clinically, and is divided into 5 subtypes (type A, AB, B1, B2, and B3) based on the WHO classification histologically. The 4th edition of the WHO classification is the latest and it was published in 2015. Thymic carcinoma is completely different from thymoma histologically, and is more aggressive than thymoma. Thymic neuroendocrine tumors are divided into well differentiated neuroendocrine carcinomas (carcinoid tumor) and poorly differentiated neuroendocrine carcinomas which consist of large cell neuroendocrine carcinoma and small cell carcinoma. Mature teratoma is usually seen as a mass containing soft-tissue, fluid, fat, or calcium attenuation, or any combination of the four. Malignant germ cell tumors are divided into seminoma and non-seminomatous tumors. This tumor manifests as a large homogeneous soft tissue mass and mimics lymphoma with nodal coalescence. Anterior mediastinal cysts are thymic cyst and pericardial cyst, etc. Simple cyst appears as well-defined water-attenuation mass with imperceptible wall. At first, I would like to show the new definition of mediastinal compartments which is useful for making a differential diagnosis in my lecture. Then, I will demonstrate CT and MR images of prevascular mediastinal tumors, and talk how to differentiate and diagnose these entities.

Retroperitoneal Leiomyosarcoma From the Radiologic Pathology Archives.

Leiomyosarcoma is a malignant neoplasm that shows smooth muscle differentiation. It is the second most common sarcoma to affect the retroperitoneum. Retroperitoneal leiomyosarcomas may grow to large sizes before detection and may be an incidental finding at imaging. When symptomatic, retroperitoneal leiomyosarcoma may cause compressive symptoms, including pain. Retroperitoneal leiomyosarcoma most commonly manifests as a large soft-tissue mass, with areas of necrosis. The most frequent pattern of growth is an entirely extravascular mass. Less commonly, leiomyosarcoma may demonstrate both extravascular and intravascular components. Rarely, retroperitoneal leiomyosarcomas are completely intravascular, typically arising from the inferior vena cava. Given its variable imaging features, a large variety of neoplastic and nonneoplastic conditions are included in the differential diagnosis of retroperitoneal leiomyosarcoma. In this review, the authors discuss retroperitoneal leiomyosarcoma, with emphasis on the pathologic basis of disease, and illustrate the multimodality imaging appearances of retroperitoneal leiomyosarcoma using cases from the Radiologic Pathology Archives of the American Institute for Radiologic Pathology. The authors review important differential considerations of retroperitoneal leiomyosarcoma, focusing on the extravascular pattern of growth, and emphasize clinical and imaging features that help radiologists differentiate leiomyosarcoma from the most frequent mimics. The information presented in this review will aid radiologists in fulfilling their key roles in the diagnosis, operative planning, and follow-up of patients with retroperitoneal leiomyosarcoma.

Renal cell carcinoma in ectopic-pelvic kidney: A rare case with review of literature.

The incidence of renal cell carcinoma in a pelvic kidney is rare, and has only been reported in a small number of cases. We report a 50-year-old male patient presented with vague abdominal pain and without hematuria. CT scan showed large heterogeneous soft tissue mass arising from a left pelvic kidney with areas of necrosis measuring 8.4×8.4×7.5 cm. Histopathology after radical nephro-ureterectomy showed grade II clear-cell renal carcinoma. Renal cell carcinoma of ectopic kidney is a rare disease. Even though the presentation might be atypical and challenging, the treatment strategy is still the same as for tumors of orthotopic kidneys.

Role of Ultrasound in the Diagnosis Approach of Malignant Solitary Fibrous Tumor

This is a case study of solitary fibrous tumor (SFT), which is a rare neoplasm of mesenchymal origin that comprises less than 2% of all soft tissue tumors. SFT located in the extremities, especially in the legs, has a high possibility of developing malignancy. The case study presented demonstrates a sonogram which identified an inhomogenous hypoechoic solid lesion located in the subcutaneous layer of the femoral region. The use of Doppler showed hypervascular activity in the hyperechoic area. This finding was consistent with malignant SFT and confirmed by histopathologic exam. The possibility of an SFT should be a diagnostic consideration with any large soft tissue mass in extremities. This is a further consideration with the diagnostic medical sonography findings demonstrating a hypoechoic, well-defined mass that has a large collateral feeding vessel and displaces the adjacent structures.

Magnetic resonance features of meningeal solitary fibrous tumors.

The aim of the present study was to investigate magnetic resonance (MR) features of meningeal solitary fibrous tumors (SFTs) in order to improve their recognition. The study retrospectively analyzed MR manifestations in 12 cases of meningeal SFTs confirmed by surgery. The lesions were analyzed in terms of the site of their growth, growth mode, morphology, size, changes in the MR signal and the edge of the focus. The tumors were malignant in 3 cases, benign in 7 cases and borderline in 2 cases. A total of 3 cases spanned the tentorium cerebelli, 3 spanned the falx and another case was close to the falx. Overall, 4 superficial tumors were accompanied by adjacent bony destruction. One case was located at the triangular area created by the right lateral ventricles. The tumors were all lobular, with a large diameter and more cystic areas in the center of the focus. The signals were often heterogeneous. The parenchyma in the tumors was significantly enhanced. For certain tumors, the signal was usually inhomogeneous and not uniform. The MR features of a SFT were often similar to other intracranial tumors and easily misdiagnosed. There were certain innate characteristics, for example, the tumor was often a solitary large soft-tissue mass with an irregular edge and a clear boundary, with a lobulated contour, and was widely involved with other tissues. The tumors often grew across either the falx or tentorium cerebelli. A significantly inhomogeneous signal was found and either a low or low-high mixed signal on T2-weighted images in particular. These features are useful for the differential diagnosis of SFTs and other tumors.

256 Monophasic Synovial Sarcoma Presenting as a Parapharyngeal Mass—Report of a Rare Case

Synovial sarcoma (SS) is an aggressive soft tissue sarcoma, most commonly arising in the peri-articular tissue of extremities in young adults, harboring a specific chromosomal translocation t(X;18)(p11.2;q11.2). SS is a misnomer because it does not arise from the synovium; it appears to arise from pluripotent stem cells that are capable of differentiating into mesenchymal and/or epithelial structures and lacks synovial differentiation. SS accounts for ~5%-10% of soft tissue sarcomas. Occasionally, it arises in the head and neck region and carries a poor prognosis. Morphologically, SS can be biphasic (BSS), monophasic (MSS), or poorly differentiated. We report a rare case of MSS presenting as a parapharyngeal mass. The patient is a 27-year-old-man presenting with left-sided facial and mandibular pain. Imaging showed large parapharyngeal soft tissue mass in the region of the left pterygoid musculature measuring 3.6 x 2.9 x 2.5 cm with focal calcifications. He underwent resection of this mass, which showed spindle cell neoplasm with variably prominent hemangiopericytoma-like vascular pattern. Vague nuclear palisading was also noted. Immunohistochemical stains were focally positive for cytokeratins (AE1/AE3, CK7, CK8 (Cam5.2), and CK19), calponin, calretinin, EMA, GFAP, and synaptophysin with Ki67 labeling being 25%-30%. The tumor cells were negative for CD34, CD117, desmin, HMB45, myogenin, P63, S100, and SMA. RT-PCR showed SYT/SSX2 fusion transcript. Combining all, the diagnosis of MSS-spindle cell type was confirmed. Based on AFIP data, ~3% of SS arise in this location. SS is a rare entity to be encountered in the head and neck region and is often a challenge in terms of diagnosis, especially the MSS type. The differential of monophasic tumors is fibrosarcoma, malignant schwannoma, and hemangiopericytoma. We report this case of MSS because of its rare presentation as a parapharyngeal mass. Clinicians and pathologists should be aware of this unusual location and presentation of SS.

Cytodiagonosis of Cystic Nodular Hidradenoma Presenting as Thigh Mass

Nodular hidradenoma is an unusual benign adnexal tumor arising from the excretory duct of sweat glands. It usually occurs in elderly females and commonly involves the scalp, neck, trunk and extremities. Although it is diagnosed on histopathology, knowledge of cytological features can help in their early detection. Moreover, long standing undiagnosed cases can rarely turn into malignancy. Thus, it is essential to identify these tumors in advance to treat them timely. Therefore, we herein describe certain salient cytological features of nodular hidradenoma that occurred as a large nodular soft tissue mass on the right thigh of an elderly female.