Question
What are the red structures (as marked by a black arrow) scattered throughout this biopsy as shown in the photomicrograph below of a cerebellar mass in a 13 year old male?
A. Blood vessels.
B. Fungal organisms.
C. Lewy bodies.
D. Rosenthal fibers.
Show Answer
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Correct Answer » D
Explanation
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The structure shown by a black arrow in the photomicrograph above is Rosenthal fibers.
Rosenthal fibers (or Rosenthal bodies) are eosinophilic structures present in great numbers in pilocytic astrocytomas. Pilocytic astrocytomas are indolent tumors that usually occur in childhood and often affect the cerebellum. Composed of long, thin, pilocytic (“hair-like”) astrocytes, these tumors tend to grow very slowly, even if a higher-grade histologic appearance is present.Rosenthal fibers are present in pilocytic astrocytoma – but they are not specific for that tumor. They are also seen in areas of long-standing gliosis and in Alexander disease. They are weird little structures that contain two heat-shock proteins and ubiquitin.
