Image Quiz: A skinny Lab with a swollen face

A 2-year-old neutered male Labrador retriever was presented for evaluation of severe facial swelling and marked weight loss. The owners noted that the swelling had been increasing over the past couple of weeks. A complete blood count, serum chemistry profile, and skull radiographic examination were performed.

Oblique view

Lateral view

Ventrodorsal view

From the radiographs presented here, what's the most likely diagnosis?

a) Renal secondary hyperparathyroidism

b) Cranial mandibular osteopathy

c) Occipital dysplasia

d) Multilobular osteochondrosarcoma