Extra-axial chordomas in the pediatric population are extremely rare and diagnostically challenging; only four cases have been previously reported with ages ranging from 13 to 20 years. We report a primary extra-axial chordoma involving the soft tissue directly dorsal and ulnar to proximal phalanx in the right thumb of a 12-year-old girl who presented with worsening right thumb pain for 1.5 years. The diagnosis was confirmed by excisional biopsy demonstrating proliferation of large, polygonal epithelioid cells with diffuse expression of pan-cytokeratin and brachyury. The patient required repeat excision for local recurrence seven months later. Since then, she has remained disease free through 15 months surveillance. Extra-axial chordomas share the same histopathological and immunohistochemical characteristics with their axial counterparts and should be considered in the differential diagnosis for any extra-axial bone or soft tissue mass with epithelioid morphology.

An 87-year-old patient reported a nodular, progressively enlarging mass of the anterior nasal septum leading to partial obstruction of the nostrils. The tumor showed no infiltration of the subcutis, bone, or paranasal sinuses in imaging or intraoperatively. Histological examination revealed a chondroid tumor with lobular growth and physaliferous cell morphology. Immunohistochemistry revealed a brachyury-positive tumor without EWSR1 rearrangement, leading to the diagnosis of a chondroid chordoma. The reported case demonstrates the differential diagnostic considerations pertaining to this rare tumor, which can also have an untypical and very rare extra-axial location. Review of the literature identified 34 primary extraosseous chordomas of the nose, nasopharynx, and paranasal sinuses, and allowed the nasal chordoma presented herein to be included in this group of extra-axial chordomas.
UNASSIGNED: Ein 87-jähriger Patient berichtete über eine knotige, größenprogrediente Struktur des anterioren Nasenseptums mit partieller Verlegung der Naseneingänge. In der Bildgebung sowie intraoperativ zeigte sich die Raumforderung lokal begrenzt, ohne Anzeichen der Infiltration von Subkutis, Knochen sowie der angrenzenden Sinus paranasales. Histologisch zeigte sich ein chondroider Tumor mit lobulärem Wachstum sowie physaliphorem Zytoplasma. Durch die immunhistochemische Untersuchung konnte bei Positivität für Brachyury und Negativität für ein EWSR1(Ewing-Sarcoma-Breakpoint-Region)-Rearrangement die Diagnose eines chondroiden Chordoms gestellt werden. Der vorliegende Fall belegt die differenzialdiagnostischen Überlegungen zu diesem Tumor, der per se selten ist, aber auch an untypischen extraaxialen Stellen lokalisiert sein kann. Nach Literaturrecherche wurde eine Übersicht aller von uns identifizierten 34 primären extraossären Chordome der Nase, des Nasopharynx und der paranasalen Sinus erstellt und der vorgestellte Fall in diese Übersicht eingeordnet.

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Poorly differentiated chordoma (PDC) is a newly described variant of chordomas, which is not considered as a subtype yet, but has its own distinct features in terms of morphology, immunohistochemical and molecular characteristics, and clinical outcome. To provide a brief review of clinical, morphological, immunohistochemical, and molecular features of poorly differentiated chordoma. PubMed search using keyword \'poorly differentiated chordoma\'. A critical review of all studies with a total of 53 cases using inclusion criteria of involvement of axial skeleton (vertebra and clivus), INI1 loss (either with the aid of immunohistochemistry or various molecular techniques), and immunohistochemical brachyury expression. PDC is characterized by a young population with slight female predominance, clivus/cervix location, multinodular sheets of epithelioid cells with eosinophilic cytoplasm and prominent pleomorphism, and loss of SMARCB1/INI1 expression, which can be demonstrated both with immunohistochemical and molecular studies, and is unexpected for other types of chordoma. However, classical chordomas lacking SMARCB1/INI1 expression were also reported and how to classify these cases has not been addressed yet. This unique entity is a candidate to be recognized and distinguished from other types of chordoma or SMARCB1-deficient tumors which are clinically important differential diagnoses that represent a challenging task for the pathologists.

Chordomas are rare bone malignancies that are thought to arise from remnants of the notochord and usually are located in the axial skeleton. Immunophenotypical matching neoplasms primarily found in appendicular locations, referred to as extra-axial chordoma, are rarely encountered by radiologists, surgeons, and pathologists. Only a few of these cases have been described in the literature with only one intra-articular case with involvement of the knee joint. We present the first case of an intra-articular extra-axial chordoma of the wrist. Diagnostic imaging patterns were initially ambiguous and histopathological reprocessing was crucial in order to determine the diagnosis of an intra-articular neoplasm with co-expression of cytokeratins, S-100 protein, and brachyury.

Extra-axial chordoma is a chordoma that occurs in non-axial locations. It is a very rare tumor, with 20 cases reported to date; 14 in bone and six in soft tissue. Of the 14 skeletal extra-axial chordomas, ten were intramedullary and four were intracortical. We report the first case of parosteal extra-axial chordoma arising in the second metacarpal bone, expressing brachyury on immunohistochemical analysis, and describe the pathologic and radiologic findings. We suggest that extra-axial chordoma can occur in parosteal bone lesions or the hand, without features of bone distribution or bone-specific sites.

Chordoma is a rare malignant bone tumor that can arise anywhere along the central neural axis and many involve head and neck sites, most commonly the skull base. The relative rarity of these tumors, combined with the complex anatomy of the head and neck, pose diagnostic challenges to pathologists. This article describes the pertinent clinical, pathologic, and molecular features of chordomas and describes how these features can be used to aid in formulating a differential diagnosis. Emphasis is placed on key diagnostic pitfalls and the importance of incorporating immunohistochemical information into the diagnosis.

Identification of loss of SMARCB1/INI1 expression in poorly differentiated (PD) chordoma in pediatric patients suggests that PD chordoma is an entity molecularly distinct from conventional chordoma or atypical teratoid/rhabdoid tumor, which is also characterized by loss of SMARCB1/INI1 expression by inactivating mutation of the SMARCB1/INI gene. So far, around 20 cases of pediatric PD chordoma with loss of SMARCB1/INI1 expression have been reported. Here, we report two cases of pediatric PD chordoma with loss of SMARCB1/INI1 expression, which is very rare among the pediatric chordoma types. Both patients presented clival masses on preoperative MRI. Histologically, both tumors had nonclassic histologic features for conventional chordoma: sheets of large epithelioid to spindle cells with vesicular nuclei and prominent nucleoli. Both cases revealed nuclear expression of brachyury, loss of SMARCB1/INI1 expression and lack of embryonal, neuroectodermal, or epithelial component. One case showed heterozygous loss of EWSR1 gene by break-apart fluorescence in situ hybridization that reflected loss of SMARCB1/INI1 gene. Based on the clival location and histologic findings along with the loss of SMARCB1/INI1 expression and positivity for nuclear brachyury staining, the final pathologic diagnosis for both cases was PD chordoma.

Primary extra-axial chordomas have been rarely documented, especially in the appendicular bones. Until now, nine such cases, objectively confirmed with positive brachyury immunostaining, have been reported. A 42-year-old male presented with pain in his right tibial tuberosity (shin) of 2-3 years duration without any associated swelling. He denied complaints related to any other lesion elsewhere in his body. Plain radiograph of his lower limbs revealed a large, eccentric, well-defined, lytic lesion containing internal septae with a narrow zone of transition and a sclerotic medullary border in the upper metaphysis of his right tibia, associated with a pathological fracture. There was no other lesion identified in his spine on radiographic imaging. Biopsy sections revealed a tumour composed of polygonal cells with moderate to abundant eosinophilic to vacuolated/\'bubbly\' cytoplasm (physaliphorous cells) arranged in lobules within a conspicuous myxoid matrix. By immunohistochemistry, tumour cells were diffusely positive for pan cytokeratin (AE1/AE3), epithelial membrane antigen (EMA), CK19, S100P, meso (HBME1) and Brachyury/T. Diagnosis of an a primary extra-axial chordoma was finally rendered. Subsequently, the patient underwent bone grafting from his iliac crest. The present case constitutes as the 11th documented case of an extra-axial, intraosseous chordoma and the 10th such case occurring in the appendicular bones. Literature review of similar cases; their diagnostic mimics along with diagnostic and therapeutic implications of such cases are discussed herewith.