Utility of Squash Cytology in Spinal Lesions with Special Reference to Ki67 Immunostain.

BACKGROUND: Squash cytology is of significant importance in intraoperative consultation of central nervous system (CNS) pathology. There are several studies on squash cytology of CNS lesions, and only a few of them deal with spinal lesions alone. AIMS: (1) To evaluate intraoperative squash cytology of spinal lesions. (2) To correlate cytological diagnosis with histopathological diagnosis and assess the diagnostic accuracy. (3) To study Ki67 expression on squash smears and determine whether it can assist in grading spinal tumours on cytology. MATERIALS AND METHODS: A prospective study was conducted on 68 patients with clinico-radiologically diagnosed lesions of the spine. Intraoperative squash smears were stained with haematoxylin-eosin (H&E) stain, Papanicolaou (Pap) stain, and May-Grünwald-Giemsa (MGG) stain. Subsequently, histological diagnosis was made. Ki67 immunostaining was performed on squash smears and histology sections. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of squash cytology in spinal lesions were 84.6, 100, 100, 23.1, and 80.88%, respectively. On immunocytochemistry, the mean Ki67 labelling indices for grade I, II, and III tumours were 0, 0.33 and 9%, respectively. CONCLUSION: Squash smear cytology is a rapid intraoperative technique for diagnosing spinal lesions, with high specificity and high positive predictive value. It is more effective in diagnosing neoplasms than non-neoplastic lesions. Ki67 immunostaining can be done on cytology smears to effectively differentiate between WHO grade I and grade II spinal tumours.

Intramedullary gangliogliomas: histopathologic and molecular features of 25 cases.

Gangliogliomas are uncommon glioneuronal tumors, which usually arise in the cerebral hemispheres and occasionally in the brain stem. Gangliogliomas occurring in the spinal cord are extremely rare. In this study, we analyzed the clinical, histopathologic, and molecular features of 25 spinal gangliogliomas. The cases included in our series affected mostly children and young adults (15 males and 10 females; mean age, 20 years; median age, 14 years; age range, 1-72 years) and were predominantly localized in the cervical and thoracic spine. From the clinical point of view (detailed follow-up available for 9 pediatric cases; mean follow-up: 2 years 10 months; range, 3 months to 5 years 10 months), most patients showed stable disease after subtotal resection. Radiotherapy was rarely used as adjuvant treatment. Histologically, gangliogliomas (WHO grade I) (21 cases) showed features largely similar to their supratentorial counterparts. Anaplastic gangliogliomas (World Health Organization grade III) (4 cases) showed features of anaplasia (including high cellularity and increased mitotic and proliferation activity). From a molecular point of view, only 2 tumors (2/19, 11%) harbored a BRAF(V600E) mutation. In conclusion, although spinal gangliogliomas display histologic and clinical features similar to their supratentorial counterparts, they show a relatively low frequency of BRAF(V600E) mutations, alteration otherwise common in hemispheric and brain stem gangliogliomas.

Melanotic schwannoma of thoracic spinal root mimics metastatic melanoma: a potential pitfall for misdiagnosis.

Melanotic Schwannoma (MS) is a kind of rare subtypes of Schwannoma. In this tumor, amounts of melanin always mislead inexperienced pathologists to a diagnosis of primary or metastastic melanoma. Different from the ordinary Schwannoma, MS is considered as a low malignant nerve sheave tumor. Here we present a case of MS arising from the thoracic spinal and initially was misdiagnosed as metastastic melanoma. But the patient followed a benign course, without recurrent in 30 months follow-up.

Extragonadal malignant germ cell tumors: a clinicopathological and immunohistochemical analysis of 48 cases at a single Chinese institution.

Primary extragonadal malignant germ cell tumors (EMGCTs) are rare and characterized by the location in the midline of the body, including mediastinum, CNS, retroperitoneum and coccyx. EMGCTs present with different clinical and biologic characteristics in different tumor locations. Accurately diagnosing MEGCTs would be very difficult by performing on HE staining alone, and requires immunohistochemical verification. This study was to investigate the biological feature of EMGCTs and diagnostic value of immunohistochemical markers OCT3/4, CD117, PLAP, AFP, ß-HCG and CD30 in EMGCTs. A retrospective study was performed on 48 patients with EMGCTs. EMGCTs were found to occur predominantly in males, especially for mediastinal MGCTs. The tumor locations included mediastinum, CNS and retroperitoneum. The mediastinum and CNS were the most common sites of EMGCTs. Seminoma/germinomas (64.6%) was the most common histological subtypes of EMGCTs. Chest pain, dyspnea, cough and fever were the most common clinical presentations in mediastinal MGCTs. Headache, visual disturbances, endocrine abnormalities, and signs of increased intracranial pressure were common clinical symptoms in CNS MGCTs. Abdominal mass with or without pain, backache and weight loss were common clinical presentations in retroperitoneal MGCTs. PLAP, CD117 and OCT3/4 were highly expressed in seminomas/gernimomas. CD30, EMA and CK AE1/3 staining were positive in embryonal carcinoma. AFP and ß-HCG positive staining are characteristic in yolk sac tumors and choriocarcinoma, respectively. Patients with seminomas/germinomas had a better prognosis than those with NS/G-GCTs. Our finding suggests that the accurate diagnosis of EMGCTs is critical not only for predicting the tumor progression but also for patient management. Immunohistochemical markers have become an important tool in the diagnosis and differential diagnosis of EMGCTs.

Survival analysis of breast cancer subtypes in patients with spinal metastases.

STUDY DESIGN: We conducted a retrospective cohort study of 151 patients with breast cancer spinal metastases. OBJECTIVE: To investigate the influence of breast cancer subtypes on survival duration of patients with breast cancer spinal metastases, and to aid spine surgeons in selecting treatments on a more precise basis. SUMMARY OF BACKGROUND DATA: There is lack of knowledge about specific prognosis of patients with spinal metastases in various breast cancer subtypes. Estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (Her-2) status are the key factors in determining breast cancer subtypes and predicting patients' response to adjuvant treatments. METHODS: Until August 2013, we retrieved 151 surgically treated patients with breast cancer spinal metastases and followed up all the patients for at least 2 years. Survival duration analysis and Cox proportional hazards regression model unadjusted and adjusted by age were used. RESULTS: Patients with ER-negative (-) breast cancer had 11 months shorter median survival duration (10.6 vs. 21.5 mo) and 48% higher mortality risk (P=0.03) than those with ER-positive (+) breast cancer. Patients with PgR (-) status had 59% higher mortality risk than those with PgR (+) status (P=0.02). Hormone receptor (HR) status is a combination of ER and PgR status. Patients with HR (-) status had an 11-month shorter median survival duration and 52% higher mortality risk (P=0.01) than patients with HR (+) status. Human epidermal growth factor receptor 2 subtypes had similar median survival duration and mortality risk. Patients with triple-negative breast cancer had a median survival duration of only 9.9 months. CONCLUSION: Patients with spinal metastases with ER/HR (-) status and triple-negative breast cancer could be downgraded from score "5" to "3" in Tokuhashi scoring system and from "slow growth" to "moderate growth" in Tomita scoring system. Spine surgeons should be critical before performing high-risk extensive surgery in patients with ER/HR (-) status, and especially, in those with triple-negative status. LEVEL OF EVIDENCE: 3.

A unique cutaneous presentation of Burkitt lymphoma.

Few reports of cutaneous Burkitt lymphoma exist in the literature. Here, the authors describe the case of a human immunodeficiency virus-positive individual with the rare diagnosis of cutaneous Burkitt lymphoma. Three weeks before the development of his cutaneous lesions, the patient experienced bilateral lower extremity paralysis, and an epidural mass was found. Bone marrow biopsy findings and serum protein electrophoresis seemed consistent with multiple myeloma. The visible appearance of the skin lesions raised concern for cutaneous involvement by myeloma; however, the skin biopsy showed morphological and immunohistochemical features of Burkitt lymphoma. In this case report, the authors discuss the histopathologic findings of the cutaneous lesions in consideration with the bone marrow biopsy findings.

Primary sacral non-germinal center type diffuse large B-cell lymphoma with MYC translocation: a case report and a review of the literature.

An 85-year-old man presented with pain and numbness in the left buttock, and physical examination revealed an approximately 7 cm mass extending from the first to the third sacral vertebrae; biopsy of the mass led to the diagnosis of CD10-negative, BCL6-weakly positive, MUM1-positive, non-germinal center (non-GC) type diffuse large B-cell lymphoma (DLBCL). Furthermore, serological testing showed negative results for Epstein-Barr virus (EBV) infection, and fluorescence in situ hybridization (FISH) revealed a MYC translocation. Radiographs showed no remarkable osteolytic bone destruction, and the patient was staged with Stage IAE. After 8 cycles of rituximab therapy and 6 cycles of CHOP therapy, complete remission has been maintained until now, approximately 1 year after the treatment. Primary sacral lymphoma is very rare, with only 6 reported cases, including the present one. A review of the reported cases revealed that the disease predominantly affects elderly men, is usually non-GC-type DLBCL and stage IAE, measures approximately 2-7 cm in diameter in general, and does not show early recurrence after chemotherapy or chemoradiotherapy. There is no report in the literature yet of primary sacral DLBCL with MYC translocation, and this is the first case report. On the other hand, 35 cases of CD10-negative DLBCL with MYC translocation, including the present one, have been reported, and a review of the reported cases showed that the disease predominantly affects Asians, middle-aged or elderly men, shows positivity for either BCL6 or MUM1 and negativity for EBV, and has a high international prognostic index and poor prognosis.

Primary cardiac pleomorphic sarcoma presenting as back pain in an 18-year-old man.

Soft-tissue sarcoma is the most prevalent primary malignant cardiac tumor. This sarcoma usually presents with cardiac manifestations secondary to local obstruction or arrhythmias; very rarely does it present with initial symptoms of distant metastasis. We discuss the unusual case of an 18-year-old man who emergently presented with acute-on-chronic back pain. Imaging revealed a lesion on the 12th thoracic vertebra and a large mass arising from the left atrium. The cardiac mass was resected, and immunohistochemical analysis revealed it to be a pleomorphic sarcoma that had metastasized to the spine. The patient died 2 years later of diffuse metastases. In addition to the patient's case, we discuss the nature and treatment of cardiac sarcoma.

A major response to trabectedin in metastatic malignant fibrous histiocytoma of the vertebra: a case report and review of the literature.

Malignant fibrous histiocytoma is an aggressive tumor, the most common soft-tissue sarcoma of adult age. It is usually located in the extremities and retroperitoneum, and very rarely there is skeletal involvement. Surgery is the preferred treatment in early disease; in advanced disease, chemotherapy is the main therapeutic strategy. We present a 25-year-old female patient diagnosed with a vertebral mass in T5 with a severely compromised spinal cord. She underwent surgical decompression and the pathological findings were consistent with malignant fibrous histiocytoma. After several surgical treatments she had pulmonary progression and was therefore started on chemotherapy. She had a very poor response to most of the administered regimens until she initiated trabectedin 1 mg/m 2 every three weeks. She showed a significant improvement with a major response of the lung metastases. This report indicates that trabectedin is an active drug in advanced, previously treated metastatic malignant fibrous histiocytoma.

[Clinico-pathological and molecular aspects of diagnostic and prognostic value in gliomas]. / Aspectos clinicopatologicos y moleculares de valor diagnostico y pronostico en gliomas.

INTRODUCTION: Diffuse infiltrative gliomas, the most common primary brain tumours, account for almost 80% of malignant brain tumours. 60-70% of gliomas are astrocytic and over 80% of these tumours is considered high grade malignancy (grade III and IV) according to current World Health Organization classification. Infiltrating gliomas include diffuse astrocytomas, oligodendrogliomas and oligoastrocytomas. AIM: To review the clinical and histological features of cerebral gliomas, and molecular alterations that add relevant information for novel approaches in diagnosis, prognosis and treatment. DEVELOPMENT: The current gold standard diagnosis of these tumours relies on histopathological classification, which provides a grading of malignancy as a predictor of biological behaviour. However emerging molecular abnormalities have been discovered in the last years and these molecular changes are playing an increasingly prominent role as predictive biomarkers or in the development of diagnostic and prognostic. Now the neuropathologist is in crossroads between pathology and molecular biology and he plays a significant role in implementation of treatments and/or clinical trials. CONCLUSIONS: The study of proteomics and molecular biomarkers should complement the histopathological analysis and sometimes allows to determine direct or indirect predictive factors as well as the study of affected pathways which may become selective therapeutic targets.

Primary intrathoracic dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is defined as a low-grade sarcoma derived from an uncertain cell of origin in the reticular dermis. We report a fibrosarcomatous variant of DFSP (FS-DFSP) that arose primarily in the deep thoracic soft tissue. The patient was a 9-year-old girl who presented with dyspnea and low-grade fevers without a clinically detectable mass or a history of skin lesion. Imaging studies revealed a 10-cm mass entirely confined within the thoracic cavity. Three years after a marginal excision with adjuvant chemotherapy and radiotherapy, the tumor recurred in the paraspinal region. Histologically, the primary and recurrent tumors comprised a high-grade spindle cell sarcoma, with a small component of storiform, low-grade, CD34-positive spindle cells, classic for an ordinary DFSP. The diagnosis of FS-DFSP was confirmed molecularly by the demonstration of a COL1A1-PDGFB fusion by fluorescence in situ hybridization and reverse transcription-polymerase chain reaction analyses. To our knowledge, this is the first documented case of a genetically confirmed deep-seated DFSP without an associated superficial soft tissue or dermal component. The implication of this case on expanding the clinical spectrum of DFSP will have to be elucidated in future studies by applying molecular pathologic tools in deep-seated sarcomas in the proper morphologic context.

NUT midline carcinoma: report of 2 cases suggestive of pulmonary origin.

In this study, we report 2 pediatric cases of nuclear protein of the testis (NUT) midline carcinoma (NMC) suggestive of pulmonary origin: case 1 was a 14-year-old Japanese boy and case 2 was a 7-year-old Japanese girl. Initial symptoms of both cases were prolonged cough and chest pain, and the case 2 patient also complained of lumbago and lumbar mass due to bone metastases. Imaging studies revealed that pulmonary tumors from both patients were located at the hilar region of the lower lobe. Biopsies of the tumors showed undifferentiated carcinoma in case 1 and combined undifferentiated and squamous cell carcinoma in case 2. Despite intensive treatment with chemotherapy and radiation, progression of neither tumor was controlled, and both patients died of the tumors at 1 year (case 1) and 4 months (case 2) after onset of disease. Both tumors were diffusely positive for p63 and NUT expression and were partially positive for various cytokeratins. Reverse transcription polymerase chain reaction analysis and subsequent direct sequencing revealed that the bromodomain-containing protein 4-NUT chimeric gene was present in tumor tissue of both patients, leading to a diagnosis of NMC. The tumor cells of case 1 were also positive for thyroid transcription factor-1 expression, but those of case 2 were negative. Histologic examination of the surgically removed lung tumor of case 1 indicated that the origin of the tumor was basal cells of the bronchiolar epithelia.

Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: report of two clinical cases.

BACKGROUND: Malignant peripheral nerve sheath tumor (MPNST) is a sarcoma with a high grade of malignancy originating in the nerve sheath components, fibroblasts, perineural cells, and Schwann cells. It is associated with neurofibromatosis type 1 (NF-1) with a risk of 10-13%. CLINICAL CASES: We present two cases of NF-1-associated MPNST. The first patient presented moderate pain with no apparent cause, in addition to the presence of intraspinal lesion demonstrated by nuclear magnetic resonance imaging (NMRI), which was managed surgically on two occasions. Histologically, it corresponded to a neurofibromatosis lesion in transition with malignant neoplasm. The second case manifested with thoracic kyphoscoliosis, pain, and an increase in volume. Associated with the deformity, MRI showed a withering tumor in the posterior thoracic region (T1-T8), observing an infiltrating, cellular sarcomatous neoplasm with immunopositivity for S-100 protein and vimentin. CONCLUSIONS: MPNSTs are sarcomas with a high index of recurrence with the ability to produce distant metastasis during early stages. Despite wide resection, patients did not survive due to the advancement and size of the lesions (determining factors in the prognosis). Due to the progressive growth of MPNST and the anatomic difficulty for its approach, there should be strict surveillance of patients with NF-1 for early detection of malignant transformation in these lesions.

Tumor de vaina nerviosa periférica maligno asociado a neurofibromatosis tipo 1: informe de dos casos / Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: report of two clinical cases

Introducción: El tumor de vaina nerviosa periférica maligno (TVNPM) es un sarcoma de alto grado de malignidad, originado de componentes de las vainas nerviosas, fibroblastos, células perineurales y células de Schwann, que se asocia a neurofibromatosis tipo 1 con un riesgo de 10 a 13 %. Casos clínicos: Se presentan dos casos de TVNPM asociado a neurofibromatosis tipo 1. El primero presentó dolor moderado sin causa aparente, además de lesión intrarraquídea en resonancia magnética nuclear, manejada quirúrgicamente en dos ocasiones. Histológicamente correspondió a lesión neurofibromatosa en transición con neoplasia maligna. El segundo se manifestó con cifoescoliosis torácica, dolor y aumento de volumen. Asociado a la deformidad, la resonancia magnética mostró tumor en la región torácica posterior (T1 a T8), que fue resecado; se identificó neoplasia sarcomatosa infiltrante, muy celular, con inmunopositividad para proteína S100 y vimentina. Conclusiones: Los TNVPM son sarcomas con alto índice de recurrencia, capaces de producir metástasis a distancia desde etapas tempranas. A pesar de la resección amplia, los pacientes descritos no sobrevivieron dado el avance y tamaño de las lesiones. Por el crecimiento progresivo de los TNVPM y la dificultad anatómica para su abordaje, deberá tenerse un control estrecho de los pacientes con neurofibromatosis tipo 1 a fin de identificar tempranamente la transformación maligna de las lesiones.

BACKGROUND: Malignant peripheral nerve sheath tumor (MPNST) is a sarcoma with a high grade of malignancy originating in the nerve sheath components, fibroblasts, perineural cells, and Schwann cells. It is associated with neurofibromatosis type 1 (NF-1) with a risk of 10-13%. CLINICAL CASES: We present two cases of NF-1-associated MPNST. The first patient presented moderate pain with no apparent cause, in addition to the presence of intraspinal lesion demonstrated by nuclear magnetic resonance imaging (NMRI), which was managed surgically on two occasions. Histologically, it corresponded to a neurofibromatosis lesion in transition with malignant neoplasm. The second case manifested with thoracic kyphoscoliosis, pain, and an increase in volume. Associated with the deformity, MRI showed a withering tumor in the posterior thoracic region (T1-T8), observing an infiltrating, cellular sarcomatous neoplasm with immunopositivity for S-100 protein and vimentin. CONCLUSIONS: MPNSTs are sarcomas with a high index of recurrence with the ability to produce distant metastasis during early stages. Despite wide resection, patients did not survive due to the advancement and size of the lesions (determining factors in the prognosis). Due to the progressive growth of MPNST and the anatomic difficulty for its approach, there should be strict surveillance of patients with NF-1 for early detection of malignant transformation in these lesions.

Bone cement deposition patterns with plasma-mediated radio-frequency ablation and cement augmentation for advanced metastatic spine lesions.

BACKGROUND AND PURPOSE: Combining percutaneous plasma-mediated radio-frequency (pmRF) ablation with vertebral body augmentation offers an alternative treatment to surgical intervention options for advanced metastatic spinal lesions and is particularly useful for cases with cortical destruction and/or epidural extension. This study evaluates bone cement deposition patterns and extravasation in treated vertebral bodies in relation to the metastatic lesion after using this combined approach. MATERIALS AND METHODS: Retrospective assessments of CT images performed before/after the procedures were evaluated in 37 patients (44 levels) with advanced metastatic lesions. A void was created in the anterior portion of the tumor-infiltrated vertebral body by using a bipolar plasma-mediated radio-frequency-based wand, followed by deposition of bone cement. Pain measured by visual analog scale score was recorded preprocedure and 2-4 weeks afterward. RESULTS: In 19 (43%) levels, 90%-100% of the cement was deposited in the anterior two thirds of the vertebral body. In 34 levels (77%), 75% or more of the cement was deposited in the anterior two thirds of the vertebral body. In 13/15 (86%) levels with posterior lesions, cement was deposited anterior to the lesion. No extravasation was observed in 13 levels (29.5%). Two clinically insignificant incidences of epidural extravasation were noted. Pain relief after the procedure was reported by 25/28 (89.5%) patients with available data. CONCLUSIONS: pmRF ablation may allow greater cement-deposition control, increasing the likelihood of successfully stabilizing the anterior two thirds of the vertebral body. This combined technique appeared particularly useful in cases with posteriorly located lesions. The incidence of cement extravasation was relatively high but clinically insignificant.

Ewing's sarcoma family tumors mimicking primary central nervous system neoplasms.

Ewing's sarcoma family tumors (ESFTs) and embyronal tumors of the central nervous system are malignant primitive neuroectodermal tumors (PNETs) that can arise in the central nervous system, bones, or soft tissues. When ESFTs involve the central nervous system or nearby structures the diagnosis depends on cytogenetics and immunohistochemistry as these tumors can appear otherwise histologically identical to central PNETs. Correct diagnosis is essential as the treatment paradigms for both entities differ. We present two cases of isolated central nervous system presentations of ESFTs mimicking primary central nervous system neoplasms.

Pediatric extra-renal rhabdoid tumors with unusual morphology: a diagnostic pitfall for small biopsies.

The diagnosis of malignant rhabdoid tumor (MRT) is straightforward if the typical, large eosinophilic rhabdoid cells are identified. We report on two diagnostically challenging cases of pediatric extra-renal MRTs which, when evaluated at incisional biopsy, were composed exclusively of small- to medium-sized round cells with focal spindling, lacking rhabdoid phenotype. This morphology, along with a polyphenotypic immunoprofile, including the expression of vimentin/CD99/cytokeratins/alpha-smooth muscle actin and vimentin/CD99/S-100 protein in case 1 and case 2, respectively, suggested the possibility of Ewing sarcoma (EWS)/PNET. However, molecular analyses failed to show the presence of the EWS/FLI-1 and EWS/ERG fusion transcripts, indicative of the most common translocations, i.e., t(11;22)(q24;q12) and t(22;21)(q22;q12), occurring in this tumor family. The revision of both cases included an immunohistochemical analysis with a commercially available anti-INI1 protein antibody. Immunohistochemistry, showing the absence of INI1 expression in neoplastic cells, strongly supported the diagnosis of MRT. Ultrastructural studies, performed on formalin-fixed tissues, were consistent with the diagnosis of MRT. This study suggests including anti-INI1 protein antibody in the immunohistochemical panel when evaluating pediatric tumors with ambiguous morphological and immunohistochemical features, particularly from small biopsies. A careful evaluation of clinical, pathological, and molecular findings is the key to a correct diagnostic approach of pediatric tumors.

Intramedullary amputation neuromas associated with spinal ependymomas.

We report 5 spinal intramedullary masses containing combined ependymoma and traumatic neuroma. The ependymomas, grade II "cellular" types, were intermixed with or separate from wavy, vaguely fascicular tissue that contained multiple axons immunoreactive for neurofilament protein. The neuromas presumably arose from small perivascular nerve twigs that have been implicated in the pathogenesis of intramedullary neuromas in non-neoplastic spinal diseases. Pathologists should be aware of this distinctive intramedullary tissue that is not to be confused with a neoplasm.

Dedifferentiated chordoma of the thoracic spine with rhabdomyosarcomatous differentiation. Report of a case and review of the literature.

A case of spinal thoracic chordoma involving the T9 vertebra in a 70-year-old male patient, destroying the vertebral body and invading the vertebral canal with compression of the spinal cord, is presented. The patient was referred to our neurosurgical unit with a history of an irradiated metastatic adenocarcinoma to the thoracic vertebra, a diagnosis that was rendered 3 years earlier at another hospital on presentation. This misdiagnosis was likely due to the absolute rarity of thoracic vertebral chordomas (2%-3% of all chordomas), the higher frequency of metastatic deposits to the vertebrae from visceral cancers in the elderly, the limited amount of biopsy material available for histologic examination, and the epithelial phenotype of the tumor (keratin/EMA positive). The patient underwent second palliative surgery with subtotal piecemeal removal of the tumor bringing relief of the neurologic symptoms. The bulk of the tumor was represented by a high-grade pleomorphic sarcoma with adjacent areas of atypical chordoma. Small foci of conventional chordoma were also found. The previous histologic slides were also reviewed, which were consistent with the areas of atypical chordoma. Small targeted tissue fragments from areas of (atypical) chordoma and from sarcomatous areas were recovered for electron microscopy. The fine features of chordoma and focal rhabdomyoblastic differentiation were found with the latter retrospectively supported by immunohistochemical detection of striated muscle markers. A final diagnosis of dedifferentiated chordoma with rhabdomyoblastic differentiation was finally established. Rhabdomyoblastic metaplasia is a novelty in dedifferentiated chordoma. The patient died after 5 months. Autopsy was not requested.