Discussion
The earliest reported case of hyperparathyroidism was documented in 1930
(2) and since then the further classification into primary, secondary
and tertiary forms has helped to directappropriate treatment.In the
United Kingdom, it is suggested approximately one to four people per
thousand have a diagnosis of hyperparathyroidism (8). Brown tumoursoccur
more commonly in cases of primary than secondary hyperparathyroidism.
However, most cases clinicians see are with secondary
hyperparathyroidism as it is more prevalent in the general population
(7).
The clinical manifestations of hyperparathyroidism are bone pain,
insufficiency fractures and renal colic. Dental clinical findings can
include drifting teeth and delayed dental development (1). There are
also associated radiographic changes. An increased production of
parathyroid hormone results in increased osteoclastic activity and bone
resorption. On radiographs there is often cortical thinning and
generalised bony changes which can range from osteopenia to a granular
or ground glass appearance to the bone of the skeleton and jaws
(10).Loss of lamina dura in patients with hyperparathyroid disease is a
well-recognised consequence but it isactually only evident in about 10%
of cases (8). There are also a range of other characteristic bony
changes that can occur such as a ‘pepper –pot’ skull (10).Brown tumours
can arise when the hyperparathyroid status is prolonged and the most
common sites are the mandible, clavicles, ribs, pelvis and femur. Brown
tumours can be single or multiple.Osteitis fibrosa cystica describes a
more severe skeletal manifestationwith multiple cyst-like Brown tumours
affecting the bone (10,11). Soft tissue calcifications may also be
evident on imaging.
The panoramic radiograph identified multiple radiolucent lesions in the
jaws. A range of differential diagnoses were considered to explain the
multiple radiolucent lesions:
- Metastatic bone tumours are the most common malignant tumours of the
jaw. Carcinomas of the thyroid are known to metastasize to the
mandible (10). Metastasis would be expected to have poorly defined,
permeative margins and would destroy bone rather than allow it to
expand and remodel.
- Lymphoreticular tumours of the bone such Myeloma and Langerhans Cell
Histiocytosis can both present as multiple jaw radiolucencies.
- Myeloma presenting as multiple proliferations of plasma cells in the
bone marrow. The usual radiographic appearance includes multi-focal
lesions of punched out radiolucent appearances. These lesions have
well defined but not corticated borders.
- Langerhans cell histiocytosis is the increased proliferation of
langerhans cells and eosinophilic leucocytes. It can manifest as a
solitary eosinophilic granuloma, multiple lesions
(Hand-Schüller-Christian
disease) or disseminated disease (Letterer-Siwe disease). The bone
lesions in all three circumstances are radiographically similar,
also well defined, non-corticated and without expansion. Often the
periodontal bone support is destroyed, leading to teeth appearing to
“float” or appear to be “standing in space”(10). Langerhans cell
histiocytosis only tends to affect children, adolescents and young
adults.
- Giant cell lesions also known as ‘granulomas’can present as single or
multiple jaw radiolucencies. Radiographically and histologically Brown
tumours are indistinguishable from giant cell lesions but they occur
in patients that do not have hyperparathyroidism. These patients are
usually younger and any patient with a giant lesion over thirty years
hyperparathyroidism should be excluded with blood tests (10,11).