Lopsided occiputal bone in a dog
A 14-month-old intact male German shepherd dog was presented to the clinic for a preadoption evaluation. As the clinician was running the routine examination, a centered-looking bump on the back of the head (calvarium) was noticed. As it was kind of lopsided, the owner was so concerned about the growth that it might be a kind of tumor. Initially some attempts to aspirate the growth were unsuccessful since it was so dense. On the other hand, it was perfectly symmetrical like an occipital bone. On more precise palpation, It seemed to be besides the occipital bone, but then again, we were confused. An X-ray was ordered to see the nature of the growth and if it was attached the occipital bone. The radiographic study consisted of lateral and DV views of skull. A soft tissue swelling was seen in dorso-caudal of calvarium but no destruction on underlying bone was seen at that time.
At that stage the differential diagnosis included hematoma, abscess and neoplasia. So a fine needle aspiration was highly recommended. As no bone filaments were embedded in it, the neoplasia was ruled out. Under general anesthesia, a fine needle aspiration was carried out. Smears were made on glass microscopic slides, fixed and stained using Wright's and Giemsa stain technique.
The smear had appearance of blood except that platelets were absent. A number of macrophages and plump fibroblasts were seen. Some macrophages contained phagocytosed red cells or haemoglobin breakdown product in the form of bluish black haemosiderin granules or haematoidin crystals.
The dog was put anti-inflammatory drug (meloxica 7.5, 0.1mg/kg PO OID) for a week. The bump gradually went down and after two weeks it was completely gone.