Hypervascular: similar to hyaline vascular features, but seen in iMCD rather than UCD. Includes regressed germinal centers, follicular dendritic cell prominence, hypervascularity in interfollicular regions, and prominent mantle zones with an "onion-skin" appearance. Mixed: presence of a combination of hyaline vascular/hypervascular and plasmacytic features in the same lymph node.UCD most commonly demonstrates hyaline vascular features, but plasmacytic features or a mix of features may also be seen. iMCD more commonly demonstrates plasmacytic features, but hypervascular features or a mix of features are also seen. All cases of HHV-8-associated MCD are thought to demonstrate plasmablastic features—similar to plasmacytic features, but with plasmablasts present. The clinical utility of subtyping Castleman disease by histologic features is uncertain, as histologic subtypes do not consistently predict disease severity or treatment response. Guidelines recommend against using histologic subtype to guide treatment decisions. Staining with latency-associated nuclear antigen (LANA-1), a marker for HHV-8 infection, should be measured in all forms of Castleman disease but is positive only in HHV-8-associated MCD.Diseases other than Castleman disease can present with similar histologic findings in lymph node tissue, including:
Infectious causes: Epstein-Barr virus, human immunodeficiency virus, tuberculosis
Autoimmune diseases: Systemic lupus erythematosus, rheumatoid arthritis
Lymphoproliferative disorders: lymphoma, autoimmune lymphoproliferative syndrome

History
Unicentric Castleman disease was first described in a case series by Benjamin Castleman in 1956. By 1984, a number of case reports had been published describing a multicentric variant of the disease and with some reports describing an association with Kaposis sarcoma. In 1995, the association between HHV-8 and Castleman disease was described in patients with HIV.
In sacralization, the L5-S1 intervertebral disc may be thin and narrow. This abnormality is found by X-ray.Sacralization of L6 means L6 attaches to S1 via a rudimentary joint. This L6-S1 joint creates additional motion, increasing the potential for motion-related stress and lower back pain/conditions. This condition can usually be treated without surgery, injecting steroid medication at the pseudoarticulation instead. Additionally, if L6 fuses to another vertebra this is increasingly likely to cause lower back pain. The presence of a sixth vertebra in the space where five vertebrae normally reside also decreases the flexibility of the spine and increases the likelihood of injury. Hemivertebrae
Hemivertebrae are wedge-shaped vertebrae and therefore can cause an angle in the spine (such as kyphosis, scoliosis, and lordosis). Among the congenital vertebral anomalies, hemivertebrae are the most likely to cause neurologic problems. The most common location is the midthoracic vertebrae, especially the eighth (T8). Neurologic signs result from severe angulation of the spine, narrowing of the spinal canal, instability of the spine, and luxation or fracture of the vertebrae. Signs include rear limb weakness or paralysis, urinary or fecal incontinence, and spinal pain. Most cases of hemivertebrae have no or mild symptoms, so treatment is usually conservative. Severe cases may respond to surgical spinal cord decompression and vertebral stabilization. Associations
Recognised associations are many and include:
Aicardi syndrome,
cleidocranial dysostosis,
gastroschisis 3,
Gorlin syndrome,
fetal pyelectasis 3,
Jarcho-Levin syndrome,
OEIS complex,
VACTERL association.The probable cause of hemivertebrae is a lack of blood supply causing part of the vertebrae not to form.