Superficial Anaplastic Lymphoma Kinase-Rearranged Myxoid Spindle Cell Neoplasm in the Buttock: A Case Report.

Anaplastic lymphoma kinase (ALK) is detected in both normal and oncological developmental tissues. Among ALK-related tumors, superficial ALK-rearranged myxoid spindle cell neoplasm (SAMS) is a rare, soft tissue tumor characterized by the immunophenotypical co-expression of CD34 and S100. Here, we describe a patient with this rare tumor and outline its clinical and radiological characteristics. A 28-year-old woman with diabetes, hypertension, and panic disorder presented with discomfort caused by a rubbery mass on the left buttock that had persisted for 10 years. Computed tomography revealed a multilobulated hypodense mass with small internal enhancing foci, posing challenges for the exact diagnosis of the lesion. The entire lesion was excised with clear resection margins. An 8.0 × 6.0 cm, well-circumscribed tumor with a lobular growth pattern was observed in the deep subcutaneous tissue. Light microscopy revealed epithelioid, ovoid, and spindle-shaped cells with a reticular cordlike pattern. Immunohistochemistry results were positive for S100, CD34, and vimentin. Break-apart fluorescence in situ hybridization assay results for ALK were also positive. These findings were consistent with those of SAMS. This case suggests that SAMS should be considered when identifying large nonspecific masses during clinical and imaging evaluation.

Myopericytoma of the Right Middle Finger: A Case Report of an Uncommon Perivascular Neoplasm.

This report describes the case of a 29-year-old male who presented with painless swelling on the volar aspect of his right middle finger. The initial clinical impression was consistent with an epidermal inclusion cyst. A plain radiograph of the lesion revealed a circumscribed superficial nodular soft tissue mass confined to the dermis of the affected finger. Following surgical excision and subsequent histopathologic examination, the lesion was ultimately identified as a myopericytoma (MPC). The occurrence of MPCs in the finger is uncommon; thus, a high level of suspicion is required to consider it as one of the differential diagnoses for painless nodules in this anatomical location. Surgery serves as the primary method for treatment, and histopathologic evaluation plays a crucial role in confirming the diagnosis and ruling out malignancy.

Soft tissue vascular tumor-like lesions in adults: imaging and pathological analysis pitfalls per ISSVA classification.

OBJECTIVES: To compare the magnetic resonance imaging (MRI) and Doppler ultrasound (DUS) findings with the pathological findings of soft tissue vascular tumors (STVTs) according to the 2018 ISSVA (International Society for the Study of Vascular Anomalies) classification to differentiate vascular tumors from vascular malformations. METHODS: This retrospective study included patients with STVTs who underwent contrast-enhanced MRI and pathological analysis at our hospital between 2010 and 2020. The presumptive diagnosis based on the on-site imaging and histological analysis was compared with imaging and histological analysis conducted off-site utilizing the ISSVA criteria. RESULTS: This study included 31 patients with 31 vascular tumors located in the head and neck (n = 3), trunk (n = 2), and extremities (n = 26). The off-site pathological analysis confirmed benign vascular tumors in 54.8% of cases (non-involuting congenital hemangioma: 35.5%; epithelioid hemangioma: 13%; pyogenic granuloma: 3%; and spindle cell hemangioma: 3%). Based on the off-site histological analysis, 25.8% were reclassified as having a vascular malformation whereas three had other benign lesions. Only phleboliths were associated with a vascular malformation (p = 0.03). The concordance between off-site MRI and pathological findings was fair (k = 0.3902 (0.0531-0.7274)), whereas that between on-site and off-site pathological analyses was poor (k = -0.0949 (-0.4661 to 0.2763)). CONCLUSION: Benign vascular tumors have non-specific imaging features on imaging with some overlap with atypical vascular malformations. Therefore, histological analysis is recommended. Imaging and pathological analyses should be performed in accordance with the ISSVA classification to minimize inter-observer discrepancies. CRITICAL RELEVANCE STATEMENT: Imaging features of benign vascular tumors on MRI are non-specific, leading to discrepancies with pathological findings and potential overlap with atypical vascular malformations. Imaging and histological analyses should be performed in accordance with ISSVA guidelines to improve patient management. KEY POINTS: The imaging features of benign vascular tumors are non-specific. Histological analysis is recommended for soft tissue vascular tumors in adults. Analyses of soft tissue vascular tumors should be performed in accordance with ISSVA guidelines.

An aggressive soft-tissue sarcoma of the extremity: A myxofibrosarcoma, grade 3 (FNCLCC system).

We report a case of myxofibrosarcoma of the posterior region of the femur, part of the group of soft-tissue sarcomas: a set of rare and heterogeneous tumors with various subtypes and different prognostic. It is characterized by local infiltrative activity and an extremely high rate of local recurrence. A 58-year-old man came to the Radiology Department to examine a voluminous round and expansive formation of the posterior thigh region. The patient stated that the mass had grown suddenly for about 3 months, maybe after a trauma, increasing in volume exponentially and causing him discomfort, embarrassment, and pain. The result of the first diagnostic approach, with the US, was unexpected and suspicious, and the radiologist wanted to do first a CT, and then maybe plan an MRI. The CT revealed an inhomogeneous density formation and in MRI the mass resulted to be compatible, with the radiologic pattern, with the diagnosis of a sarcoma of the soft tissue. The physicians had already alerted the pathological anatomy, as they suspected something malignant. So, some days after the MRI examination, the patient underwent histological sampling, confirming the suspicion: a myxofibrosarcoma (stage III) of the posterior region of the femoral region. The patient started on radio and chemotherapy, which increases survival and in the hope of reducing the size of the mass, and a strict follow-up was posed before doing the surgery.

Soft tissue tumor of metastatic non-small cell lung carcinoma: A rare case report.

INTRODUCTION AND IMPORTANCE: It is estimated that 1 out of 5 patients with cancer will experience bone metastasis. With non-small cell lung cancer by itself having 220.000 reported cases per year, but the prevalence of soft tissue metastasis from lung cancer is only 2.3 % making it commonly overlooked as a possible metastasis site. CASE PRESENTATION: Male presents with a lump and pain on the right upper arm. A 8 cm × 8 cm mass was palpated under the biceps. CT-scan showed a lung lesion on the anterior segment. Shoulder MRI showed a dense, lobulated, and indefinitely demarcated soft tissue mass approximately 5.6 cm × 7.8 cm × 8.8 cm. The patient was treated with wide excision of the tumor. Core biopsy showed a metastatic adenosquamous carcinoma with suspected primary lesion from the respiratory tract. Treatment with targeted chemotherapy and radiotherapy were then done to the patient. The patient was discharged without any complications and is still at remission at the 6 months post-operative checkup. CLINICAL DISCUSSION: Soft tissue metastasis of lung cancer cell is a rare but a very real phenomenon. In our case the diagnosis of the soft tissue mass as a metastasis from the lungs was decided on a clinical, physical, radiological, and histological basis without using immunohistochemistry. CONCLUSION: MRI, biopsy, and immunohistochemistry are traditionally needed to confirm the diagnosis but in select cases, radiological and microscopic examinations along with clinical correlation are enough to ascertain the diagnosis. While it is rare, a soft tissue metastasis should always be suspected in lung cancer patients that have a palpable mass.

Subcutaneous leiomyosarcoma in a cynomolgus macaque (Macaca fascicularis).

Leiomyosarcoma, a malignant tumour originating from smooth muscle cells, has rarely been documented in non-human primates. In this case study, a 7-year-old female cynomolgus macaque (Macaca fascicularis) presented with a rapidly growing mass overlying the left elbow joint. Radiographs indicated the presence of a soft tissue neoplasm without any associated bone involvement. The mass was surgically resected. Histological and immunohistochemical analyses revealed spindle-shaped cells with eosinophilic cytoplasm that resembled smooth muscle cells, exhibiting positive immunoreactions for vimentin, desmin and smooth muscle actin and a negative reaction for pan-cytokeratin. This is the first reported case of subcutaneous leiomyosarcoma in a cynomolgus macaque and provides important insights into the incidence and characteristics of this condition in this species.

Update on immunohistochemistry in bone and soft tissue tumors: Cost-effectively replacing molecular testing with immunohistochemistry.

Soft tissue tumors form part of a challenging domain in diagnostic pathology owing to their comparative rarity, astonishing histologic diversity, and overlap between entities. Many of these tumors are now known to be defined by highly recurrent, or, in some instances, unique molecular alterations. Insights from gene profiling continue to elucidate the wider molecular landscape of soft tissue tumors; many of these advances have been co-opted by immunohistochemistry (IHC) for diagnostic applications. There now exists a multitude of antibodies serving as surrogate markers of recurrent gene fusions, amplifications, and point mutations, which, in certain settings, can replace the need for more resource and time-intensive cytogenetic and molecular genetic analyses. IHC presents many advantages including rapid turnaround time, cost-effectiveness, and interpretative reproducibility. A sensible application of these immunohistochemical markers complemented by a working knowledge of the molecular pathogenesis of bone and soft tissue tumors permits accurate diagnosis in the majority of cases. In this review, we will outline some of these biomarkers while emphasizing molecular correlates and highlighting interpretative challenges and pitfalls.

Superficial CD34 fibroblastic tumors and PRDM10-rearranged soft tissue neoplasm: An evolving diagnosis.

Superficial CD34 fibroblastic tumors (SCD34FT) and PRDM10-rearranged tumors (PRTs) are mesenchymal tumors that have recently received increased scientific attention due to their irrefutable similarities yet debatable relationship. A 74-year-old male presented to the dermatology clinic with a violaceous, well-defined nodule on the left medial knee of 2-year duration. Shave biopsy demonstrated spindle cells arranged in a vaguely storiform pattern forming fascicles. Immunohistochemical stains were positive for vimentin, CD68, CD10, and CD34 diffusely. ERG, S-100, HMB45, and SOX-10 were negative. Molecular studies identified a mediator complex subunit 12 (MED12)-PR/SET Domain 10 (PRDM10) gene fusion thus favoring confirming the diagnosis of a PRT. Our patient underwent wide local excision with negative margins and had no complications. This case aims to provide context for considering SCD34FT and PRT as intersecting entities and to discuss a diagnostic approach when encountering these tumors.

Oral palisaded encapsulated neuroma; a diagnosis seldom suspected clinically.

Key Clinical Message: Palisaded encapsulated neuroma (PEN) is generally seen in the head and neck area as an asymptomatic nodule with the same color as the surrounding skin and rarely occurs in the oral cavity. The exact etiology of PEN is not known, but there is evidence supporting the role of trauma as its etiological factor. Abstract: Palisaded encapsulated neuroma (PEN) is one of the benign nerve sheath tumors of Schwann cell origin, which is commonly found in the skin of the head and neck area, and rarely occurs in the oral cavity. Its exact etiology is unknown, but there is evidence that supports the role of trauma as an etiological factor. Here we present a case of PEN in the hard palate of a 30-year-old patient and review the differential diagnoses of these nerve sheath tumors of the oral cavity.

Challenging Diagnostic Dilemma: Mesenteric Desmoid Tumor Masquerading as Perforated Peritonitis.

Desmoid fibromatosis is a rare benign neoplasm of the soft tissue. Primary desmoid neoplasms rarely occur in the small bowel and are primarily found in patients with a previous abdominal surgery or irradiation history. They are challenging to diagnose at the time of presentation due to a lower incidence and their non-specific presentation making it difficult to distinguish from other intra-abdominal neoplasms, such as gastrointestinal stromal tumors (GISTs), which may present with similar symptoms. We like to present a case of a 34-year-old male with a four-day history of abdominal pain with worsening severity and one episode of non-bloody vomiting. Physical examination was significant for generalized abdominal tenderness with positive rebound and board-like rigidity. A computed tomography (CT) scan of the abdomen showed the presence of a lower abdominal mass of unknown etiology with free air foci and free intraperitoneal fluid either due to rupture of the suspicious mass or secondary to infection by an air-producing organism. The patient was immediately taken for emergency surgery, the tumor was resected successfully, and a specimen collected was sent for histopathology, which came out to be a desmoid tumor. We aim to highlight the importance of keeping a broad differential diagnosis in a patient with acute abdomen and symptoms of peritonitis.

INternational Soft Tissue saRcoma ConsorTium (INSTRuCT) consensus statement: Imaging recommendations for the management of rhabdomyosarcoma.

Rhabdomyosarcoma is the most common soft-tissue neoplasm in the pediatric population. The survival of children with rhabdomyosarcoma has only marginally improved over the past 25 years and remains poor for those with metastatic disease. A significant challenge to advances in treatment of rhabdomyosarcoma is the relative rarity of this disease, necessitating years to complete clinical trials. Progress can be accelerated by international cooperation and sharing national experiences. This necessitates agreement on a common language to describe patient cohorts and consensus standards to guide diagnosis, treatment, and response assessment. These goals formed the premise for creating the INternational Soft Tissue saRcoma ConsorTium (INSTRuCT) in 2017. Multidisciplinary members of this consortium have since developed international consensus statements on the diagnosis, treatment, and management of pediatric soft-tissue sarcomas. Herein, members of the INSTRuCT Diagnostic Imaging Working Group present international consensus recommendations for imaging of patients with rhabdomyosarcoma at diagnosis, at staging, and during and after completion of therapy. The intent is to promote a standardized imaging approach to pediatric patients with this malignancy to create more-reliable comparisons of results of clinical trials internationally, thereby accelerating progress in managing rhabdomyosarcoma and improving survival.

Understanding a mass in the paraspinal region: an anatomical approach.

The paraspinal region encompasses all tissues around the spine. The regional anatomy is complex and includes the paraspinal muscles, spinal nerves, sympathetic chains, Batson's venous plexus and a rich arterial network. A wide variety of pathologies can occur in the paraspinal region, originating either from paraspinal soft tissues or the vertebral column. The most common paraspinal benign neoplasms include lipomas, fibroblastic tumours and benign peripheral nerve sheath tumours. Tumour-like masses such as haematomas, extramedullary haematopoiesis or abscesses should be considered in patients with suggestive medical histories. Malignant neoplasms are less frequent than benign processes and include liposarcomas and undifferentiated sarcomas. Secondary and primary spinal tumours may present as midline expansile soft tissue masses invading the adjacent paraspinal region. Knowledge of the anatomy of the paraspinal region is of major importance since it allows understanding of the complex locoregional tumour spread that can occur via many adipose corridors, haematogenous pathways and direct contact. Paraspinal tumours can extend into other anatomical regions, such as the retroperitoneum, pleura, posterior mediastinum, intercostal space or extradural neural axis compartment. Imaging plays a crucial role in formulating a hypothesis regarding the aetiology of the mass and tumour staging, which informs preoperative planning. Understanding the complex relationship between the different elements and the imaging features of common paraspinal masses is fundamental to achieving a correct diagnosis and adequate patient management. This review gives an overview of the anatomy of the paraspinal region and describes imaging features of the main tumours and tumour-like lesions that occur in the region.

Monophasic pericardial synovial sarcoma in a turkish female patient: a very rare case with cyto-histopathological findings.

BACKGROUND: The aim was to present a 35-year-old female patient with diagnosis of monophasic primary pericardial synovial sarcoma (PSS) with cytopathological findings. CASE PRESENTATION: The case with back pain, palpitation and weakness, was diagnosed with pericardial effusion and suspicious mass adjacent to right heart in ultrasonography. Computerized tomography showed mass 12 × 11 × 6.5 cm in size, located in right mid-anterior pericardial area, with heterogeneous internal structure, heterogeneously contrasting right heart and prominent pressure on superior vena cava. Cytopathology of pericardial effusion showed monotonous cells with oval-spindle vesicular nuclei, less amphophilic cytoplasm, evenly distributed chromatin and inconspicuous nucleoli. The pericardial mass was resected incompletely, spindle cell mesenchymal tumor with hypercellular fascicular structure and with infiltrative margins, containing a small amount of loose myxoid stroma, occasionally necrotic areas was observed histopathologically. Immunohistochemical positive reaction was for vimentin, Bcl-2, TLE-1. Accordingly, the case was diagnosed with monophasic PSS. CONCLUSIONS: This case of monophasic primary PSS was an extremely rare malignancy diagnosed with the cytopathological findings.

Extraenteric Malignant Gastrointestinal Neuroectodermal Tumor-A Clinicopathologic and Molecular Genetic Study of 11 Cases.

Malignant gastrointestinal neuroectodermal tumors (MGNETs), also known as "gastrointestinal clear cell sarcoma-like tumors", are very rare, aggressive sarcomas characterized by enteric location, distinctive pathologic features, and EWSR1/FUS::ATF1/CREB1 fusions. Despite identical genetics, the clinicopathologic features of MGNET are otherwise quite different from those of clear cell sarcoma of soft parts. Only exceptional extraenteric MGNET (E-MGNET) has been reported. We report a series of 11 E-MGNETs, the largest to date. Cases diagnosed with MGNET and occurring in nonintestinal locations were retrieved. A clinical follow-up was obtained. The tumors occurred in 3 men and 8 women (range, 14-70 years of age; median, 33 years) and involved the soft tissues of the neck (3), shoulder (1), buttock (2), orbit (1), tongue/parapharyngeal space (1), urinary bladder (1), and falciform ligament/liver (1). Tumors showed morphologic features of enteric MGNET (small, relatively uniform, round to ovoid cells with round, regular nuclei containing small nucleoli growing in multinodular and vaguely lobular patterns, with solid, pseudoalveolar, and pseudopapillary architecture). Immunohistochemical results were S100 protein (11/11), SOX10 (11/11), synaptophysin (3/10), CD56 (7/9), CD117 (3/9), DOG1 (0/4), ALK (4/8), chromogranin A (0/10), HMB-45 (0/11), Melan-A (0/11), tyrosinase (0/4), and MiTF (0/11). Next-generation sequencing results were EWSR1::ATF1 (7 cases), EWSR1::CREB1 (3 cases), and EWSR1::PBX1 (1 case). The EWSR1::PBX1-positive tumor was similar to other cases, including osteoclast-like giant cells, and negative for myoepithelial markers. A clinical follow-up (range, 10-70 months; median, 34 months) showed 4 patients dead of disease (10.5, 12, 25, and 64 months after diagnosis), 1 patient alive with extensive metastases (43 months after diagnosis), 1 patient alive with persistent local disease (11 months after diagnosis), and 4 alive without disease (10, 47, 53, and 70 months after diagnosis). One case is too recent for the follow-up. The clinicopathologic and molecular genetic features of rare E-MGNET are essentially identical to those occurring in intestinal locations. Otherwise, typical E-MGNET may harbor EWSR1::PBX1, a finding previously unreported in this tumor type. As in enteric locations, the behavior of E-MGNET is aggressive, with metastases and/or death from disease in at least 50% of patients. E-MGNET should be distinguished from clear cell sarcoma of soft parts and other tumors with similar fusions. ALK expression appears to be a common feature of tumors harboring EWSR1/FUS::ATF1/CREB1 fusion but is unlikely to predict the therapeutic response to ALK inhibition. Future advances in our understanding of these unusual tumors will hopefully lead to improved nomenclature.

Pleomorphic Rhabdomyosarcoma: A Systematic Review with Outcome Analysis and Report of a Rare Abdominal Wall Lesion.

Introduction. Pleomorphic rhabdomyosarcoma (RMS) is an aggressive and rare malignant neoplasm with a poor prognosis. As its name suggests, this tumor exhibits extensive pleomorphism with features of skeletal muscle differentiation. Due to its rarity, its diagnosis is often a clinical and pathological challenge. Since only small case series and a few scattered case reports exist in the literature, the impact of different demographic features, tumor site, and/or treatment modality on patient outcomes has yet to be extensively studied. Methods. We report a case of a pleomorphic RMS presenting atypically as an abdominal wall mass. We have also analyzed the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database to determine the factors affecting the outcome of this neoplasm. Moreover, we present a review and summary of pleomorphic RMS cases arising from the abdominal wall reported in the English language literature. Results. We found two hundred and forty-two cases of pleomorphic RMS in the SEER database. The majority of the patients were diagnosed after the age of 40, with the age of diagnosis showing a unimodal distribution. The majority of the patients were Caucasian (82%) and male (59%). Age of diagnosis, tumor stage, and surgical management significantly affected the patients' outcome, while patients' ethnicity, sex, or tumor site did not affect the outcome. We only found five previously reported cases of pleomorphic RMS arising from the abdominal wall. Conclusions. Pleomorphic RMS arising from the abdominal wall is extremely rare. Our data sheds light on the factors affecting the outcome of pleomorphic RMS. We have also discussed the challenges involving the histopathological diagnosis of this rare neoplasm and how to best approach this task.

Retroperitoneal Cystic Adenopecoma with Genetic Analysis: A Rare Neoplasm.

Lymphangiomyomatosis is a member of the PEComa family, and usually involves the pulmonary parenchyma of middle-aged females. Infrequently, it may involve abdominal and retroperitoneal lymph nodes, and rarely it has been described to be associated with fallopian tube-type ciliated epithelium co-existing in one neoplasm. To increase our understanding of this unusual tumor, we describe the morphology and genetics of one case and review the literature. We present the case of a 50-year-old female found to have 12.5 and 7.7 cm cystic retroperitoneal masses, describe its unique pathological features and review the literature on the previously reported cases. Based on its unique morphological, immunohistochemical, and molecular features we propose the term adenoPEComa to represent this entity. This case represents a rare example of adenoPEComa with lymphangiomyomatosis of the lymph nodes. It is the first example that has undergone next-generation sequencing revealing a mutation in TSC2 making it a confirmed member of the PEComa family of tumors.

Use of Ultrasound for Evaluation of a Large Undifferentiated Pleomorphic Sarcoma in the Lower Extremity of an Elderly Male.

Soft tissue sarcomas arise infrequently and make up less than 1% of all cancers. An undifferentiated pleomorphic sarcoma (UPS), formerly known as a malignant fibrous histiocytoma, is a malignant subtype of soft tissue sarcoma identified by a lack of specific immunohistochemical markers for lineage differentiation. These tumors are aggressive and enlarge rapidly with an increased risk of metastasis, thus prompt diagnosis, treatment, and post-resection surveillance are imperative. This case report demonstrates an incidental finding of a large undifferentiated pleomorphic sarcoma of the posterior thigh in an 86-year-old male initially evaluated with a bedside ultrasound.

Giant cell tumor of soft tissue of the colon: a case report and review of the literature.

BACKGROUND: A giant cell tumor (GCT) is a benign neoplasm characterized by mixture of mononuclear cells and multinucleated cells. A GCT of soft tissue (GCT-ST) is developed in various extraosseous sites, but GCT-ST of the gastrointestinal tract is very rare. GCT-ST usually has a benign course, but rare cases reported malignant potential of the tumor. Therefore, complete resection is required to prevent local recurrence or distant metastasis. CASE PRESENTATION: A 53-year-old woman was admitted for follow-up colonoscopy who underwent the colorectal endoscopic submucosal dissection (ESD) of a laterally spreading tumor at the hepatic flexure 6 months ago. A colonoscopy showed a polypoid mass about 3.5 × 2.5 cm at the previous ESD site. As endoscopic finding showed a smooth multi-nodular tumor without submucosal invasion, we performed endoscopic mucosal resection. Based on pathological and immunohistochemical findings, the lesion was diagnosed as a GCT-ST in the colon. Follow-up colonoscopy performed 6 months later revealed no evidence of recurrence. CONCLUSION: This is the first report of a GCT-ST identified in the colon. Although GCT-ST generally has a benign clinical course, complete resection should be performed to prevent local recurrence and metastasis.

Tumor neuroectodérmico primitivo primario de ovario

El tumor neuroectodérmico primitivo del ovario es un sarcoma de tejido blando de células redondas pequeñas, raro y agresivo, de origen neural que generalmente se asocia con una alta morbilidad y mortalidad. La inmunohistoquímica es un complemento útil en el diagnóstico diferencial. Se describe un caso de tumor neuroectodérmico primitivo del ovario en paciente nulípara de 21 años que refería dolor y aumento de la circunferencia abdominal. La ecografía mostró tumoración de contenido heterogéneo sólido-quística que aparentemente se originaba del anexo izquierdo. La resonancia magnética confirmó la presencia de tumoración que se extendía hacia la fosa iliaca izquierda sin afectación de órganos locales ni metástasis regionales o a distancia. Los marcadores tumorales estaban todos dentro del rango normal. Durante la laparotomía se observó tumoración de ovario izquierdo con ovario derecho normal. Se realizó salpingoforectomía izquierda debido al tamaño del tumor, resección en cuña de ovario derecho, linfadenectomía pélvica y omentectomía. El examen histopatológico reveló tumor compuesto por láminas de células redondas. Las células tumorales fueron positivas para cromogranina A, sinatrofisina, vimentina y enolasa específica de neuronas, lo que confirmó el diagnóstico de tumor neuroendocrino primitivo de ovario izquierdo, que se originaba de teratoma quístico inmaduro. La paciente rechazó la quimioterapia postoperatoria.

Primitive neuroectodermal tumor of the ovary is a rare and aggressive small round cell soft tissue sarcoma of neural origin that is usually associated with high morbidity and mortality. Immunohistochemistry is a useful adjunct in the differential diagnosis. We describe a case of a primitive neuroectodermal tumor of the ovary in a 21-yearold nulliparous patient who reported pain and increased abdominal circumference. Ultrasonography showed a solid-cystic heterogeneous tumor apparently originating from the left adnexa. Magnetic resonance imaging confirmed the presence of a tumor extending into the left iliac fossa without local organ involvement or regional or distant metastases. Tumor markers were all within the normal range. During laparotomy, a left ovarian tumor was observed with a normal right ovary. Left salpingo-oophorectomy was performed due the size of the tumor, right ovarian wedge resection, pelvic lymphadenectomy and omentectomy. Histopathologic examination revealed tumor composed of sheets of round cells. The tumor cells were positive for chromogranin A, synaptophysin, vimentin and neuron-specific enolase, which confirmed the diagnosis of a primitive neuroendocrine tumor of the left ovary originating from immature cystic teratoma. The patient refused postoperative chemotherapy.