However, these techniques cannot alone diagnose high- versus low-grade gliomas, and thus the definitive diagnosis of brain tumor should only be confirmed by histological examination of tumor tissue samples obtained either by means of brain biopsy or open surgery. The histological examination is essential for determining the appropriate treatment and the correct prognosis. This examination, performed by a pathologist, typically has three stages: interoperative examination of fresh tissue, preliminary microscopic examination of prepared tissues, and follow-up examination of prepared tissues after immunohistochemical staining or genetic analysis. Pathology
Tumors have characteristics that allow the determination of malignancy and how they will evolve, and determining these characteristics will allow the medical team to determine the management plan.Anaplasia or dedifferentiation: loss of differentiation of cells and of their orientation to one another and blood vessels, a characteristic of anaplastic tumor tissue. Anaplastic cells have lost total control of their normal functions and many have deteriorated cell structures. Anaplastic cells often have abnormally high nuclear-to-cytoplasmic ratios, and many are multinucleated. Additionally, the nucleus of anaplastic cells is usually unnaturally shaped or oversized. Cells can become anaplastic in two ways: neoplastic tumor cells can dedifferentiate to become anaplasias (the dedifferentiation causes the cells to lose all of their normal structure/function), or cancer stem cells can increase their capacity to multiply (i.e., uncontrollable growth due to failure of differentiation).Atypia: an indication of abnormality of a cell (which may be indicative of malignancy). Significance of the abnormality is highly dependent on context.Neoplasia: the (uncontrolled) division of cells.
The swelling of the amnion and chorion is characteristic of chorioamnionitis, occurring when bacteria makes its way into the amniotic fluid and creates an infection within the amniotic fluid. Diagnosis
Pathologic
Chorioamnionitis is diagnosed from a histologic (tissue) examination of the fetal membranes. Confirmed histologic chorioamnionitis without any clinical symptoms is termed subclinical chorioamnionitis and is more common than symptomatic clinical chorioamnionitis.Infiltration of the chorionic plate by neutrophils is diagnostic of (mild) chorioamnionitis. More severe chorioamnionitis involves subamniotic tissue and may have fetal membrane necrosis and/or abscess formation.Severe chorioamnionitis may be accompanied by vasculitis of the umbilical blood vessels due to the fetus inflammatory cells. If very severe, funisitis, inflammation of the umbilical cord connective tissue, occurs. Suspected clinical diagnosis
The presence of fever between 38.0°C and 39.0°C alone is insufficient to indicate chorioamnionitis and is termed isolated maternal fever. Isolated maternal fever may not have an infectious cause and does not required antibiotic treatment.When intrapartum (during delivery) fever is higher than 39.0°C, suspected diagnosis of chorioamnionitis can be made. Alternatively, if intrapartum fever is between 38.0°C and 39.0°C, an additional risk factor must be present to make a presumptive diagnosis of chorioamnionitis. Additional risk factors include:
Fetal tachycardia
Maternal leukocytosis (>15,000 cells/mm³)
Purulent cervical drainage

Confirmed diagnosis
Diagnosis is typically not confirmed until after delivery. However, people with confirmed diagnosis and suspected diagnosis have the same post-delivery treatment regardless of diagnostic status. Diagnosis can be confirmed histologically or through amniotic fluid tests such as gram staining, glucose levels, or other culture results consistent with infection.