A Case of McCune–Albright Syndrome Mimicking Paget’s
Disease of Bone
K. C¸ EFLE,
C. TAS¸C¸ IOG
N. B. ERTEN,
and M. A. KARAN
Department of Internal Medicine, Divisions of
Endocrinology and Metabolism,
General Internal Medicine, and
of Plastic and Reconstructive Surgery, Faculty of Medicine, Istanbul University, Istanbul, Turkey
McCune–Albright syndrome is a genetic disorder characterized
by polyostotic fibrous dysplasia, precocious puberty, and cafe´-
au-lait spots. The main defect is a missense mutation in the
GNAS1 gene, which results in the constitutive activation of the
␣-subunit of the Gs protein leading to overproduction of cAMP.
Clinical presentation is variable due to the mosaic pattern of
involvement of the tissues.
Herein, we present a case of McCune–Albright syndrome
(MAS) displaying the radiologic and biochemical features of
Paget’s disease of bone.
A 24-year-old woman was referred to our hospital due to
skeletal deformities and facial dysmorphism. Her history
included regular menses beginning at the age of 5 months, and
bone deformities becoming evident at the age of about 5 years.
Recently, she had been operated on due to a maxillary tumor;
its pathological assessment yielded a diagnosis of fibrous
On physical examination she was measured to be 90 cm in
height. Facial asymmetry with depression of the left maxillary
area was noted. She had extreme kyphoscoliosis and her right leg
(tibia) had a bowing deformity. Routine blood chemistry showed
a calcium level of 9.3 mg/dL, a phosphorus level in the low-
normal range (2.9 mg/dL, normal 2.7–4.5), and a high alkaline
phosphatase level (834 U/L, normal 42–98). Plasma levels of T
, TSH, LH, FSH, estradiol, DHEAS-S, testosterone, free tes-
tosterone, growth hormone, prolactin, cortisol, and ACTH were
all in the normal range. The parathyroid hormone level was 59.5
pg/mL (normal 9–55). Urinary hydroxyproline excretion was
392.3 mmol/mL creatinine (normal Ͻ30).
Radiological examination of the cranium revealed diffuse
sclerosis of the skull base, thickening of the calvarium, and
radiolucent areas (Figure 1). These changes were thought to be
most compatible with Paget’s disease of bone. Both femurs
showed widening of the bone shaft, ground glass appearance, and
cortical thinning. Whole-body scintigram revealed dense uptake
of the radiolabel in an asymmetric pattern (Figure 2). MRI scan
of the sella revealed no pituitary adenoma.
The presence of pathologically confirmed polyostotic fibrous
dysplasia and a history of precocious puberty was considered
decisive for diagnosis of MAS. The absence of cafe´-au-lait spots
does not exclude such a diagnosis, considering the mosaic nature
of the disease.
The most striking feature of the case was radiological find-
ings closely mimicking those of Paget’s disease of bone. In the
cranial radiographs, calvarial thickening, radiolucent areas re-
sembling osteoporosis circumscripta, and sclerotic changes were
considered compatible with Paget’s disease. Although these two
disorders can cause thickening of the bones, X-ray findings of
polyostotic fibrous dysplasia mimicking those of Paget’s disease
have been emphasized very infrequently.
Coexistence of both
clinical situations has also been reported.
inent osteoblasts on the surface of bone trabeculae and abnormal
lamellar bone are characteristics of Paget’s disease and distin-
guish it from fibrous dysplasia.
However, differentiating be-
tween Paget’s disease and polyostotic fibrous dysplasia should
not be difficult on clinical grounds considering the very early
onset of symptoms in the latter, particularly in the present case
where the bony deformities had become evident at the age of
about 5 years, which has not been seen in Paget’s disease. The
high urinary hydroxyproline excretion and high serum alkaline
phosphatase observed in our case may reflect the high bone
turnover associated with polyostotic fibrous dysplasia, a feature
also shared by Paget’s disease of bone.
These findings suggest
Address for correspondence and reprints: Dr. S¸u¨kru¨ Palanduz, Fevzi
Pas¸a Caddesi, Testereci Sokak, 1/10, Karagu¨mru¨k, Fatih, 34230 Istanbul,
Figure 1. Lateral radiograph of the cranium showing calvarial thicken-
ing, radiolucent areas resembling osteoporosis circumscripta, and strik-
ing osteosclerosis involving particularly the skull base.
Bone Vol. 24, No. 2
© 1999 by Elsevier Science Inc. 8756-3282/99/$20.00
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