Learning objectives
To familiarize the radiologist with a spectrum of radiographic manifestations of pseudohypoparathyroidism (PHP) type Ia,
a rare metabolic disorder.
The differential diagnosis of PHP-related skeletal abnormalities is discussed.
Background
♦ Introduction
PHP involves a heterogeneous group of disorders caused by target-organ resistance to the action of parathyroid hormone (PTH),
manifesting with diverse clinical and radiographic features.
♦ Epidemiology
◊ Prevalence: Extremely rare disorder [Japan study,
1997:
3.4 (2.6-4.2) cases per 1 million people]
◊ Gender ratio: Women/Men : 2/1
◊ Most common subtype: Ia / Rarest subtype: Ic
◊ Time of onset: Variable (from toddlerhood until late adulthood)
♦ Pathogenesis - Classification
◊ Variants:
Four PHP variants have been described: Type Ia,
Ib,
Ic...
Imaging findings OR Procedure Details
♦ Case presentation - Imaging
Radiographs of four patients,
aged 21-31 years,
having been diagnosed with PHP-Ia between toddlerhood and middle childhood,
were retrospectively reviewed.
All subjects presented with short stature,
while laboratory tests revealed increased levels of serum PTH and phosphate,
with hypocalcemia.
Several coexisting metabolic disorders were present,
predominantly hypothyroidism.
Description of cases
Patient A: 21-year-old male,
incidentally diagnosed with PHP-Ia at the age of 17 months,
while being subjected to laboratory examinations due to aortic valve stenosis.
Besides the features of PHP...
Conclusion
PHP,
though rare,
should be suspected in patients with skeletal changes such as brachydactyly,
ectopic ossifications and coned epiphyses of short tubular bones,
abnormalities mostly related with type Ia.
Plain radiographic imaging can adequately depict the vast majority of skeletal and soft-tissue changes reported.
Although individual radiographic features are not specific for diagnosing PHP,
the constellation of findings can be highly indicative of this endocrine entity.
However,
final diagnosis should always be established by laboratory studies.
References
[1] Levine M.
A.,
An update on the clinical and molecular characteristics of pseudohypoparathyroidism.
Current Opinion in Endocrinology,
Diabetes,
and Obesity,
2012; 19(6).
[2] Mantovani G.,
Clinical review: Pseudohypoparathyroidism: Diagnosis and Treatment.
The Journal of Clinical Endocrinology & Metabolism,
Oct 2011; 96(10):3020-30.
[3] Donghi V.,
Mora S.,
Zamproni I.,
Chiumello G.,
Weber G.,
Pseudohypoparathyroidism,
an often delayed diagnosis: a case series.
Cases Journal,
2009; 2:6734.
[4] Primer on the Metabolic Bone Diseases and Disorders of mineral metabolism,
7th Edition (2009).
American Society for Bone and...