Uncommon and peculiar soft tissue sarcomas: Multidisciplinary review and practical recommendations. Spanish Group for Sarcoma research (GEIS -GROUP). Part II.

Among all Soft Tissue sarcomas there are some subtypes with low incidence and/or peculiar clinical behaviour, that need to be consider separately. Most of them are orphan diseases, whose biological characteristics imply a clearly different diagnostic and therapeutic approach from other more common sarcoma tumors. We present a brief and updated multidiciplinary review, focused on practical issues, aimed at helping clinicians in decision making. In this second part we review these subtypes: Alveolar Soft Part Sarcoma, Epithelioid Sarcoma, Clear Cell Sarcoma, Desmoplastic Small Round Cell Tumor, Rhabdoid Tumor, Phyllodes Tumor, Tenosynovial Giant Cell Tumors, Myoepithelial Tumor, Perivascular Epithelioid Cell Neoplasms (PEComas), Extraskeletal Myxoid Chondrosarcoma, NTRK-fusions Sarcomas. Most of them present their own radiological and histopathological feautures, that are essential to know in order to achieve early diagnosis. In some of them, molecular diagnosis is mandatory, not only in the diagnosis, but also to plan the treatment. On the other hand, and despite the low incidence, a great scientific research effort has been made to achieve new treatment opportunities for these patients even with approved indications. These include new treatments with targeted therapies and immunotherapy, which today represent possible therapeutic options. It is especially important to be attentive to new and potential avenues of research, and to promote the conduct of specific clinical trials for rare sarcomas.

Ependimoma mixopapilar de partes blandas: descripción de un caso y revisión de la literatura / Soft tissue myxopapillary ependymoma: case report and review of the literature

El ependimoma mixopapilar de partes blandas es una neoplasia extremadamente infrecuente que se encuentra englobada dentro de los tumores ependimarios. Comunicamos el caso de un ependimoma mixopapilar de partes blandas en la región sacrococcígea en un varón de 18 años. El examen macroscópico de la pieza quirúrgica reveló la presencia de una lesión nodular bien delimitada de 8,3 cm de diámetro. Histológicamente se trataba de una proliferación tumoral de hábito epitelioide con papilas centradas por estructuras vasculares en ocasiones hialinizadas. Inmunohistoquímicamente demostró positividad para PGFA, S100, focalmente para vimentina y negatividad para CKAE1/AE3. Presentamos una revisión de la literatura y una discusión del diagnóstico diferencial (AU)

Soft tissue myxopapillary ependymoma is an extremely rare neoplasm classified as an ependymary tumour. We report a case of a soft tissue myxopapillary ependymoma in the sacrococcygeal region of an 18 year-old male. Macroscopic examination of the surgical specimen showed an 8.3 cm well-circumscribed nodular lesion. Histologically, it was seen to be a neoplastic epithelioid-like proliferation with papillae arranged around vascular structures, with occasional hyalinization. Immunohistochemistry revealed S100, GFAP and focal vimentin immunostaining but no CKAE1/AE3 expression. The differential diagnosis is discussed together with a review of the literature (AU)

Cartilage-derived tumor in a prehispanic individual from La Gomera (Canary Islands).

We present the case of a left tibia with an outgrowth at its distal metaphyseal/epiphyseal end, composed of cancellous bone, surrounding a destructive process that, on radiological examination, reaches the tibiotalar joint surface. The cancellous bone of the outgrowth is well preserved and is in continuity with intramedullary cancellous bone. The tibia belonged to a prehispanic adult individual, probably male, from La Gomera, in the Canary Archipelago. The antiquity of the sample is unknown, but radiocarbon dating of other samples ranges from 1600 to1800 years BP. The lesion is suggestive of a cartilage-derived tumor, most likely a chondrosarcoma. Other etiologic possibilities are also discussed, including osteochondroma, enchondroma, chondromyxoid fibroma or chondroblastoma.