Meningiomas are arachnoid derived tumors more frequent in women during perimenopause period. They are classified as grade I–III, accordingly to the World Health Organization (WHO) classification. The majority of these tumors are WHO grade I [1].

Macroscopically, lesions are white or yellowish with fibrous consistency, and calcification can be seen in some cases. In grade I, the meningothelial and transitional are the most commons. The histopathological findings in H&E are typical (Fig. 11.1).

The immunohistochemical signature of these lesions is the expression of epithelial membrane antigen (EMA) (Fig. 11.2) and the nucleus which is diffusely positive for progesterone receptor (Fig. 11.3). In more aggressive subtypes (anaplastic) we can see increased cellularity and high mitotic rate (4–10 in atypical and ≥20 in anaplastic). The cytoplasm becomes scarce and regional necrosis can be seen. In these cases, the tumor expresses moderate to high Ki-67 index with some focal areas in which antigen epithelial membrane and progesterone receptor are negative. Grade II and III, as well as higher proliferative index rate, correlate with poor prognosis and more aggressive behavior [1].

Paragangliomas are highly vascular tumors typically located at carotid artery and jugular bulb [2]. In general, paragangliomas have a fleshy, pink to red brown to gray appearance, due to hemorrhage or fibrosis.

The majority of these lesions seem to be sporadic. In one third, these lesions are related to some inherited syndrome. Hereditary paragangliomas have been linked to mutations in the genes encoding different subunits of the succinate dehydrogenase enzyme complex and can be part of four genetic syndromes: multiple endocrine neoplasia types 2A and 2B (MEN2) , neurofibromatosis type 1 (NF1) , von Hippel–Lindau (VHL) , and the Carney–Stratakis dyad [3].

Histologically, paragangliomas are composed of polygonal epithelioid cells arranged in compact cell nests or trabecular pattern which exhibit central located nuclei with fine clumped chromatin and moderate amount of eosinophilic granular nuclei. These cellular nests are usually supported by spindle-shaped cells (Fig. 11.4) [4–7].

The neuroendocrine confirmation can be achieved through positive immunohistochemical exam for neuron-specific enolase, synaptophysin , and chromogranin (Figs. 11.5 and 11.6). The sustentacular cells can express S-100 and glial fibrillary acidic protein (GFAP) [5, 6].

Histologic determination of malignancy is not easy in these cases because histologic features, such as nuclear pleomorphism, necrosis, mitotic rate, and local invasion, may be also seen in benign paragangliomas [8].

Schwannomas are benign neoplasms, more common in women during 4^a to 6^a decades of life. Macroscopically they are yellow to red encapsulated lesions usually circumscribed to the nerve. They commonly present vessels with thick walls and hemorrhage is not frequent.

Histologically they are divided into two patterns without prognostic implication. The Antoni A tissue type consists of compact areas of spindle cells with pink cytoplasm, while Antoni B comprises cells showing clear, vacuolated cytoplasm due to lipid accumulation (Fig. 11.7) [9]. Its immunohistochemical marker is the positiveness for S-100 protein, confirming the origin from Schwann cells [10].

Chondrosarcomas are a heterogeneous group of malignant bone tumors that share in common the production of chondroid (cartilaginous) matrix [11].

Commonly, they occur in patients over 50 years with slight male predominance and is classified into grade I–III depending on the cellular mitotic rate [12, 13].

Histologically, it exhibits abundant cartilage matrix production disposed in irregular shaped lobules, and often separated by fibrous band. High grade lesions can exhibit necrosis, increased cellularity, and frequent mitosis [11].

Regarding to molecular genetic, a mutation in EXT gene would lead to an accumulation of heparan sulfate proteoglycans in the cytoplasm and Golgi apparatus, instead of being transported to the cell surface where it would be important for normal chondrocyte proliferation and differentiation. Additionally, mutation in isocitrate dehydrogenase-1 and isocitrate dehydrogenase 2 gene (IDH-1 and IDH-2) has been liked to dedifferentiation in almost 50 % of chondrosarcomas [14–18].

The prognosis is close related to the grade, being grade III chondrosarcoma related to 10-year survival of 29–55 % [12].

Chordomas are rare, slow-growing, and locally aggressive neoplasms of bone that arise from embryonic remnants of the notochord and almost 35 %of chordomas involve the skull base [19, 20].

Histologically, these tumors are divided into three subtypes (conventional chordoma, chondroid chordoma, and chordoma with sarcomatous transformation) depending on the presence of cartilaginous or mesenquimal compounds [19, 21].

Macroscopically, these tumors exhibit a gelatinous, pink or gray appearance with solid and cystic areas. They are composed of lobes of epithelioid cells disposed in cords and separated by fibrous strands in a mucinous matrix. It presents physaliphorous cells that contain glycogen (Fig. 11.8).

Immunohistochemically is strongly positive for cytokeratin in almost all cases and is positive for EMA in up to 80 % of cases. In chondroid chordoma there is 85 % of positiveness for S-100 protein [22, 23] (Fig. 11.9).