Here is a question to get you thinking about bone pathology.

Which of the following is NOT TRUE regarding osteitis deformans?

A. Urinary hydroxyproline elevation
B. Bilateral maxilla abnormalities
C. Osteolysis circumscripta
D. X-linked pattern of inheritance
E. Polyostotic distribution

Osteitis deformans is another name for Paget disease, a common bone disorder characterized by excessive remodeling of bone. Going through the answers one by one:

A. Urinary hydroxyproline
This answer is true. Hydroxyproline is a marker of bone resorption; it’s just a protein in bone that’s released when bones are chewed up. It’s elevated in other diseases too – like metastatic carcinoma – that cause bone to be destroyed.

B. Bilateral maxilla abnormalities
This answer is also true. Patients with Paget disease may develop skull abnormalities, one of which is maxillary enlargment.

C. Osteolysis circumscripta
This answer is also true. Osteolysis circumscripta refers to the pattern of bone destruction in the skull seen early in Paget disease. A little more detail about this:   “In the skull, osteolysis is frequently seen as well-defined, often large areas of radiolucency most commonly affecting the frontal and occipital bones; these areas are referred to as osteoporosis circumscripta or osteolysis circumscripta. Both inner and outer calvarial tables are involved, with the former usually more extensively affected. This pattern is in contradistinction to that of fibrous dysplasia, which usually affects the outer table more prominently.” In the above image of a skull from a patient with Paget disease, the calvarium is thickened, the diploic space is widened, and there are ill-defined sclerotic and lucent areas throughout (these probably correspond to the “cotton wool spots” seen on xrays in the later stages of the disease.

D. X-linked pattern of inheritance
This answer is false. Although there may be a hereditary susceptibility to Paget disease, it is not X-linked.

E. Polyostotic distribution
This answer is true. “Polyostotic” just means “affecting many bones.” So the term could be used to apply to patients with Paget disease (as they often have more than one bone involved). It also applies to some patients with fibrous dysplasia. In fact, it applies to lots of different bone diseases!