In a male Friesian calf multifocal abundant black spots were observed on the lungs. When cut the black colouration extended into the lungs parenchyma. In the liver, to a lesser extent, this lesion could also be observed.

These images are consistent with a case of melanosis maculosa. It is characteristically multifocal, the location can be varied and it can affect any organ.

It cosists of well-defined, benign, focal clusters of melanocytes with melanin pigment which are congenital. It must be differentiated from melanoma (malignant neoplastic proliferation of melanocytes, see previous cases in pigs) and hematomas.

If hydrogen peroxide, potassium permanganate or any other oxidizing agent area applied to the black spotsthose are bleached by oxidation.

Multifocal black spots in the lung, extending into the lung parenchyma.

Multifocal black spots in the lung, extending into the lung parenchyma.

The spots, in this case, also could be observed in the liver.

The spots, in this case, also could be observed in the liver.