Station 10

Brain and heart from a sheep

The lungs are from a cat.

Cat lungs

Note the multifocal to coalescing, dark black nodules scattered throughout the lungs.

Question 1: Describe the lesions.

Brain: There is a regionally extensive, irregularly shaped, mild to moderate increase in the amount of black pigment in the meninges. There is a regionally extensive area in the tunica intima of the aorta that contains a moderate increase in black pigment.

Question 2: What is the significance of the lesion?

This is an example of melanosis, which is an incidental finding.

Question 3: Can you think of a disease in which melanin-producing cells DO cause problems?

This refers to the cat lungs, and is more of a 'bonus' question. The cat lungs are an example of malignant melanoma, a neoplasm derived from melanocytes (the cells that produce melanin). Unlike the examples in the sheep, in this case, the pigmented lesions are a very significant finding. This was a "FYI" type question - we have not talked about melanoma and I would not ask this on an exam.

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