Antiphospholipid antibody syndrome (APS) is characterized by recurrent thrombosis (such as deep vein thrombosis), pregnancy complications (including spontaneous abortions), and can be associated with autoimmune symptoms like joint pain and fever. The prolonged activated partial thromboplastin time (APTT) can also be seen in APS due to the presence of antiphospholipid antibodies.

The response to treatment of syphilis is best monitored by VDRL (Venereal Disease Research Laboratory test) because it is a non-specific test for syphilis that measures the presence of antibodies in the blood. It is widely used for diagnosis and monitoring the effectiveness of treatment. TPHA (Treponema pallidum hemagglutination assay) and FTA-ABS (Fluorescent treponemal antibody absorption) are both specific treponemal antibody tests, which are used for confirming the diagnosis but not as commonly for monitoring treatment response. TPI (Treponema pallidum immobilization) is a specific antibody test but less sensitive than TPHA and FTA-ABS, making VDRL a more practical choice for monitoring treatment.

Prophylactic spinal irradiation is often used in conditions like acute lymphatic leukemia and non-Hodgkin's lymphoma to prevent central nervous system involvement. However, it is not routinely used in Hodgkin's lymphoma unless there is a specific indication for it.

Medulloblastoma is a malignant brain tumor that commonly occurs in children. Due to its tendency to spread along the cerebrospinal fluid (CSF), craniospinal irradiation is an essential part of its treatment. Pilocytic astrocytomas and oligodendrogliomas typically do not require this approach.

Antiphospholipid antibody syndrome is characterized by recurrent thrombosis, recurrent fetal loss, and neurological symptoms. Thrombocytopenia (low platelet count) is often seen, while thrombocytosis (high platelet count) is not a typical feature of this syndrome.