See if you can answer the question before scrolling down too far (or you’ll see the answer!). The correct answer is right below the choices (along with explanations of the incorrect answers).

A 59-year-old male presents with severe headaches and fatigue of several months’ duration. A 4 cm, poorly-defined, necrotic left cerebral mass is found on CT and is subsequently biopsied. What is this round structure in the center of the field?

A. Psammoma body
B. Rosenthal body
C. Glomeruloid body
D. Pick body
E. Call-Exner body

The answer is C, glomeruloid body. Composed of a tuft of vascular structures, this ball-like structure is characteristic of glioblastoma. Glioblastomas are similar to anaplastic astrocytomas in that they are composed of markedly pleomorphic astrocytes in a fibrillary background. However, glioblastomas also demonstrate necrosis and vascular proliferation. The prognosis for these tumors is very poor.

Psammoma bodies are lamellated foci of calcification seen most frequently in papillary tumors, such as papillary carcinoma of the thyroid, and papillary cystadenoma of the ovary. Among brain tumors, meningiomas are the most likely to show psammoma bodies.

Rosenthal bodies (or Rosenthal fibers) are elongated, eosinophilic structures composed of heat-shock proteins and ubiquitin. They are seen in pilocytic astrocytomas, areas of long-term gliosis, and areas of reactive brain adjacent to craniopharyngiomas.

Pick bodies are cytoplasmic neuronal inclusions containing tau protein seen in Pick disease, a degenerative disorder of the central nervous system.

Call-Exner bodies are collections of neoplastic granulosa cells surrounding fluid-filled spaces in ovarian granulosa cell tumors.