McCune-Albright Syndrome Clinical Presentation

  • Author: Gabriel I Uwaifo, MBBS; Chief Editor: George T Griffing, MD   more...
 
Updated: Nov 16, 2011
 

History

  • The clinical presentation of McCune-Albright syndrome (MAS) is highly variable, depending on which of the various potential components of the syndrome predominate.
  • In cases where polyostotic fibrous dysplasia (PFD) is marked, multiple pathologic fractures are prominent early in the history (usually in childhood).
    • Bony involvement often is unilateral in distribution, although in many cases, it is found to predominate clinically on 1 side.
    • The potential presenting features include gait anomalies (eg, a limp), visible bony deformities, bone pain, and joint stiffness with pain, most often the result of secondary osteoarthrosis.
  • Symptoms begin during childhood, although in some cases, the disease is clinically silent and is discovered on routine radiographs obtained for an unrelated reason.
  • In other cases, the phenotypic affectation is mild and the onset of symptoms is considerably delayed; subtle findings can include mild facial asymmetry, dysmorphism, and a small difference in limb length.
  • Spontaneous improvement or resolution of the bony lesions does not occur. Existing bony lesions may slowly worsen or remain static, or new lesions may develop.
  • Bony lesions have been noted to worsen during pregnancy and other settings of estrogen excess. This may be due to the trophic effects of estrogen on fibrous dysplastic bone, which does possess estrogen receptors.
  • Rarely, MAS has been associated with high-output congestive heart failure similar to that seen in Paget disease.
  • Other endocrinopathies associated with MAS include the following:
    • Goiters, with or without hyperthyroidism, usually due to toxic multinodular goiter
    • Diabetes mellitus
    • Acromegaly
    • Cushing syndrome
    • Thyroid nodules (ie, adenomas, goitrous colloid/hypertrophic nodules, thyroid cancer [although this last disorder occurs only rarely])
  • The clinical history and physical examination findings may appropriately vary based on the patient's syndrome(s). The cardinal paradigm is that the endocrine gland's hyperfunction is the result of autonomous functioning nodular disease in all of these conditions.
  • Patients with myxomas often present with a history of palpable masses in the limbs, anterior abdominal wall, and/or back. These often are otherwise asymptomatic and may be painful.
  • Thyroid anomalies are found in 30-40% of patients with MAS. The incidence of these lesions is higher in males than in females.
  • The precocious puberty that characterizes MAS presents as premature thelarche or menarche, often in girls as young as 2-3 years.
  • Growth hormone excess coexisting with MAS is uncommon and generally is not found until early adulthood or midadulthood.
    • Usually, premature vaginal bleeding occurs before the onset of breast development. In some of these patients, the vaginal bleeding remains intermittent and irregular, while in others, it assumes a cyclical fashion typical of menstrual periods.
    • Other patients may have cyclical vaginal bleeding and breast enlargement related to fluctuations in serum estrogen levels.
    • Some of these patients may have normal onset of puberty at a normal age.
    • Forms of sexual precocity are observed in more than 50% of women with the syndrome.[12] Sexual precocity also occurs in male patients but is less common.
    • Patients with MAS and growth hormone excess present with the same paradoxical responses as regular patients with acromegaly upon thyrotropin-releasing hormone stimulation and upon oral glucose tolerance tests.
    • In the absence of a well-defined, surgically excisable pituitary adenoma (ie, producing growth hormone), octreotide is the treatment modality of choice. In fact, most patients present with diffuse pituitary hyperplasia rather than with the typical solitary macroadenoma of patients with sporadic acromegaly.
  • The skull and parasellar bone fibrous dysplasia (FD) that often coexist with this disorder (see image below) require technically demanding surgical treatment that is associated with a significantly increased potential for complications. The potential risk for secondary bony neoplasms precludes the use of radiation therapy in patients with MAS and pituitary adenomas.[13] This plain skull radiograph shows marked macrocranThis plain skull radiograph shows marked macrocrania, frontal bossing, and a markedly thickened bony table in patchy areas, particularly at the base of the skull and occiput. The skull also shows the hair-on-end appearance suggestive of Paget disease or poorly controlled hemoglobinopathy (eg, beta thalassemia, sickle cell disease).
  • Bromocriptine and the other dopamine receptor agonists are useful therapeutic modalities in the setting of hyperprolactinemia due to prolactinomas.
  • Preliminary studies suggest that the new dopamine agonist cabergoline may have utility in the treatment of cosecretory somatomammotropinomas.
  • Particularly in the setting of hyperprolactinemia, associated hypogonadotropic hypogonadism may be present.
  • Hyperprolactinemia in the absence of acromegaly has not been described in patients with MAS.
  • MAS typically is sporadic and is therefore very rarely associated with transmission from generation to generation.
Next

Physical

  • Café au lait spots, the classic symptom of McCune-Albright syndrome (MAS), often predominate ipsilateral to the side with more bony fractures and deformity.
    • These spots are fairly prominent, with irregular edges, and consequently are called the "coast-of-Maine" variants (as distinguished from the smaller, rounded, smooth-edged "coast-of-California" café au lait spots associated with neurofibromatosis type 1 [NF-1]).
    • These café au lait spots are larger and less numerous than are those in patients with neurofibromatosis.
    • They are difficult to notice in very young patients but can become more prominent with age.
    • The spots terminate abruptly at the midline and are most common on the side with the dominant amount of bony involvement.
    • The lesions are arranged in a segmental fashion that coincides with the developmental lines of Blaschko.
    • Common areas to look for subtle café au lait spots include the nape of the neck and the nasal clefts. However, these pigmented lesions are absent in 10-20% of patients and can be detected (by a formal dermatologic assessment) in as many as 10% of healthy subjects, making their diagnostic utility limited when unassociated with other features of MAS.
  • A few cases have been described in which MAS has been associated with either patchy or diffuse alopecia (first described by Shelley and Wood).
  • Patients with precocious puberty invariably are taller as children. However, as a result of a combination of precocious puberty, recurrent fractures, and hypophosphatemic rickets, the majority of patients with MAS have a final height below that of their peers and below their projected mid-parental height.
  • One important setting in which a patient with MAS attains normal height is that in which there is a coexisting growth hormone excess (a clinical pearl that aids in diagnosis).
Previous
Next

Causes

  • McCune-Albright syndrome (MAS) is presumed to result from a postzygotic mutational event occurring in a mosaic fashion early in embryonic life. Because of the sporadic distribution of the responsible somatic genetic mutations, it is impossible, based on the present body of knowledge, to predict the degree, extent, and type of tissue affliction.
  • The cardinal pathogenetic mechanism appears to be an activating somatic mutation of the cellular Gs alpha gene.[14] This results in constitutive hyperfunction of the cell that bears the mutated gene and expresses its product.
  • These activating Gs alpha mutations are demonstrated in the café au lait skin lesions, the fibrous dysplastic bony lesions, the gonadal tissues, and in various hyperfunctioning endocrine glands, including the thyroid and adrenal glands.
  • The finding of Gs alpha mutations is not entirely predictive of the pathologic changes associated with MAS.
    • In patients with MAS, multiple tissues are described that do not possess the mutations, in organs that seem to be clinically affected by the manifestations of the syndrome and vice versa.
    • Happle suggested that MAS results from a dominant lethal gene defect that persists by mosaicism.
    • Seven familial MAS cases have been described in the literature, suggesting a 2-hit mutation hypothesis for the pathogenesis.
  • Cases of MAS described in monozygotic twins are associated with different phenotypic manifestations.[15]
    • This suggests an initial, dominant, inherited mutation, which is responsible for the primary gene defect, followed by a somatic, sporadic cellular mutation that results in mosaicism and the variegated clinical phenotype.
    • This second hit is presumed to occur early in somatic division, as do the sporadic noninherited variants.
  • The basis for myxomas in association with polyostotic fibrous dysplasia in the setting of MAS is somewhat unclear. Mazabraud suggested that dysplasia of the tendon-to-muscle junctions may be the basis. Others have suggested that the myxomas may be caused by mechanical factors within the muscle fibers or at the tendon-muscle interface.
  • Other potential hypotheses include metabolic anomalies in soft tissues and bone during the growth period.
  • No consistent association exists of myxomas with intralesional Gs alpha mutations.
  • High oncogene expression is observed in the bony lesions, especially the c-fos oncogene. This finding may be due to secondary activation of the above oncogenes.
Previous
Proceed to Differential Diagnoses
 
 
Contributor Information and Disclosures
Author

Gabriel I Uwaifo, MBBS  Clinical and Research Attending, Assistant Professor of Medicine and Endocrinology, MedStar Clinical Research Center, MedStar Research Institute and Washington Hospital Center

Gabriel I Uwaifo, MBBS is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Physicians-American Society of Internal Medicine, American Diabetes Association, American Medical Association, American Society of Hypertension, and Endocrine Society

Disclosure: Nothing to disclose.

Coauthor(s)

Nicholas J Sarlis, MBBS, MD, PhD, FACP,  Vice President, Medical Affairs, Incyte Corporation

Nicholas J Sarlis, MBBS, MD, PhD, FACP, is a member of the following medical societies: American Association for Cancer Research, American Association for the Advancement of Science, American Association of Clinical Endocrinologists, American College of Endocrinology, American College of Physicians, American Federation for Medical Research, American Head and Neck Society, American Medical Association, American Society for Therapeutic Radiology and Oncology, American Society of Clinical Oncology, American Thyroid Association, Association for Psychological Science, Endocrine Society, European Society for Medical Oncology, New York Academy of Sciences, and Royal Society of Medicine

Disclosure: Incyte Corporation Salary Employment; Sanofi-Aventis Ownership interest Stock option/ restricted stock holder; Incyte Corporation Ownership interest Stock option/ restricted stock holder

Specialty Editor Board

Ghassem Pourmotabbed, MD†  Former Associate Professor, Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Tennessee School of Medicine and Health Science Center

Ghassem Pourmotabbed, MD† is a member of the following medical societies: American Diabetes Association, American Federation for Medical Research, and Endocrine Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS  Professor of Medicine (Endocrinology, Adj), Johns Hopkins School of Medicine; Affiliate Research Professor, Bioinformatics and Computational Biology Program, School of Computational Sciences, George Mason University; Principal, C/A Informatics, LLC

Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Endocrinology, American College of Nutrition, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Informatics Association, American Society for Bone and Mineral Research, Endocrine Society, and International Society for Clinical Densitometry

Disclosure: Nothing to disclose.

Mark Cooper, MBBS, PhD, FRACP  Head, Diabetes & Metabolism Division, Baker Heart Research Institute, Professor of Medicine, Monash University

Disclosure: Nothing to disclose.

Chief Editor

George T Griffing, MD  Professor of Medicine, St Louis University School of Medicine

George T Griffing, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Medical Practice Executives, American College of Physician Executives, American College of Physicians, American Diabetes Association, American Federation for Medical Research, American Heart Association, Central Society for Clinical Research, Endocrine Society, International Society for Clinical Densitometry, and Southern Society for Clinical Investigation

Disclosure: Nothing to disclose.

References

  1. Dumitrescu CE, Collins MT. McCune-Albright syndrome. Orphanet J Rare Dis. May 19 2008;3:12. [Medline]. [Full Text].

  2. Weinstein LS. Other skeletal diseases resulting from G protein defects--fibrous dysplasia and McCune Albright syndrome. In: Bilezikian JP, Raisz LG, Rodan GA, eds. Principles of Bone Biology. San Diego, Calif: Academic Press; 1996:877-87.

  3. Rosen D, Kelch RP. Precocious and delayed puberty. In: Becker KL, Bilezikian JP, Hung W, et al, eds. Principles and Practice of Endocrinology and Metabolism. 2nd ed. Philadelphia, Pa: JB Lippincott; 1995:830-42.

  4. Bercaw-Pratt JL, Moorjani TP, Santos XM, Karaviti L, Dietrich JE. Diagnosis and Management of Precocious Puberty in Atypical Presentations of McCune-Albright Syndrome: A Case Series Review. J Pediatr Adolesc Gynecol. Nov 1 2011;[Medline].

  5. Cavanah SF, Dons RF. McCune-Albright syndrome: how many endocrinopathies can one patient have?. South Med J. Mar 1993;86(3):364-7. [Medline].

  6. Elhaï M, Meunier M, Kahan A, Cormier C. McCune-Albright syndrome revealed by hyperthyroidism at advanced age. Ann Endocrinol (Paris). Oct 24 2011;[Medline].

  7. Zacharin M, Bajpai A, Chow CW, Catto-Smith A, Stratakis C, Wong MW, et al. Gastrointestinal polyps in McCune Albright syndrome. J Med Genet. Jul 2011;48(7):458-61. [Medline].

  8. Faivre L, Nivelon-Chevallier A, Kottler ML, et al. Mazabraud syndrome in two patients: clinical overlap with McCune-Albright syndrome. Am J Med Genet. Mar 1 2001;99(2):132-6. [Medline].

  9. Thomachot B, Daumen-Legre V, Pham T. Fibrous dysplasia with intramuscular myxoma (Mazabraud's syndrome). Report of a case and review of the literature. Rev Rhum Engl Ed. Mar 1999;66(3):180-3. [Medline].

  10. Cohen MM Jr, Howell RE. Etiology of fibrous dysplasia and McCune-Albright syndrome. Int J Oral Maxillofac Surg. Oct 1999;28(5):366-71. [Medline].

  11. Sotomayor K, Iñiguez G, Ugarte F, Villarroel C, López P, Avila A, et al. Ovarian function in adolescents with McCune-Albright syndrome. J Pediatr Endocrinol Metab. 2011;24(7-8):525-8. [Medline].

  12. de Sanctis C, Lala R, Matarazzo P. McCune-Albright syndrome: a longitudinal clinical study of 32 patients. J Pediatr Endocrinol Metab. Nov-Dec 1999;12(6):817-26. [Medline].

  13. Bhansali A, Sharma BS, Sreenivasulu P, et al. Acromegaly with fibrous dysplasia: McCune-Albright Syndrome--clinical studies in 3 cases and brief review of literature. Endocr J. Dec 2003;50(6):793-9. [Medline]. [Full Text].

  14. Chapurlat RD, Orcel P. Fibrous dysplasia of bone and McCune-Albright syndrome. Best Pract Res Clin Rheumatol. Mar 2008;22(1):55-69. [Medline].

  15. Endo M, Yamada Y, Matsuura N. Monozygotic twins discordant for the major signs of McCune-Albright syndrome. Am J Med Genet. Nov 1 1991;41(2):216-20. [Medline].

  16. Celi FS, Coppotelli G, Chidakel A, et al. The role of type 1 and type 2 5'-deiodinase in the pathophysiology of the 3,5,3'-triiodothyronine toxicosis of McCune-Albright syndrome. J Clin Endocrinol Metab. Jun 2008;93(6):2383-9. [Medline].

  17. Bulakbasi N, Bozlar U, Karademir I, et al. CT and MRI in the evaluation of craniospinal involvement with polyostotic fibrous dysplasia in McCune-Albright syndrome. Diagn Interv Radiol. Dec 2008;14(4):177-181. [Medline].

  18. Akintoye SO, Chebli C, Booher S, et al. Characterization of gsp-mediated growth hormone excess in the context of McCune-Albright syndrome. J Clin Endocrinol Metab. Nov 2002;87(11):5104-12. [Medline]. [Full Text].

  19. Mieszczak J, Lowe ES, Plourde P, et al. The aromatase inhibitor anastrozole is ineffective in the treatment of precocious puberty in girls with McCune-Albright syndrome. J Clin Endocrinol Metab. Jul 2008;93(7):2751-4. [Medline].

  20. de Araújo PI, Soares VY, Queiroz AL, Santos AM, Nascimento LA. Sarcomatous transformation in the McCune-Albright syndrome. Oral Maxillofac Surg. Sep 3 2011;[Medline].

  21. Bonat S, Shenker A, Monroe J. Papillary thyroid carcinoma (PTC) in a child with McCune-Albright syndrome (MAS): more than a random association?. Proceedings of the 82nd Annual Meeting of the Endocrine Society; Toronto, Canada. June 2000;P-2099.

  22. Collins MT, Shenker A, Monroe J. Clear cell thyroid carcinoma in a patient with McCune-Albright syndrome: Clinical description and analysis of tumor features. Proceedings of the 81st Annual Meeting of the Endocrine Society; San Diego, Calif. June 1999;P2-727.

  23. Feuillan PP. McCune Albright syndrome. In: Bardin CW, ed. Current Therapy in Endocrinology and Metabolism. 6th ed. St Louis, Mo: Mosby-Yearbook; 1997:235-9.

  24. Gurler T, Alper M, Gencosmanoglu R. McCune-Albright syndrome progressing with severe fibrous dysplasia. J Craniofac Surg. Jan 1998;9(1):79-82. [Medline].

  25. Leet AI, Chebli C, Kushner H, et al. Fracture incidence in polyostotic fibrous dysplasia and the McCune-Albright syndrome. J Bone Miner Res. Apr 2004;19(4):571-7. [Medline].

  26. Lumbroso S, Paris F, Sultan C. McCune-Albright syndrome: molecular genetics. J Pediatr Endocrinol Metab. 2002;15 Suppl 3:875-82. [Medline].

  27. Olsen BR. "A rare disorder, yes; an unimportant one, never" [editorial]. J Clin Invest. Apr 15 1998;101(8):1545-6. [Medline]. [Full Text].

  28. Raisz LG, Kream BE, Lorenzo JA. Metabolic bone disease. In: Wilson JD, Foster DW, Kronenberg HM, eds. William's Textbook of Endocrinology. 9th ed. Philadelphia, Pa: WB Saunders; 1998:1211-39.

  29. Riminucci M, Collins MT, Fedarko NS, et al. FGF-23 in fibrous dysplasia of bone and its relationship to renal phosphate wasting. J Clin Invest. Sep 2003;112(5):683-92. [Medline]. [Full Text].

  30. Spiegel AM. Inborn errors of signal transduction: mutations in G proteins and G protein-coupled receptors as a cause of disease. J Inherit Metab Dis. Jun 1997;20(2):113-21. [Medline].

  31. Spiegel AM, Weinstein LS. Inherited diseases involving g proteins and g protein-coupled receptors. Annu Rev Med. 2004;55:27-39. [Medline].

  32. Szwajkun P, Chen YR, Yeow VK. The "Taiwanese giant": hormonal and genetic influences in fibrous dysplasia. Ann Plast Surg. Jul 1998;41(1):75-80. [Medline].

  33. Tinschert S, Gerl H, Gewies A. McCune-Albright syndrome: clinical and molecular evidence of mosaicism in an unusual giant patient. Am J Med Genet. Mar 12 1999;83(2):100-8. [Medline].

  34. Uwaifo GI, Robey PG, Akintoye SO. Clinical picture: fuel on the fire. Lancet. Jun 23 2001;357(9273):2011. [Medline].

  35. Whyte MP. Rare disorders of skeletal formation and homeostasis. In: Becker KL, Bilezikian JP, Hung W, et al, eds. Principles and Practice of Endocrinology and Metabolism. 2nd ed. Philadelphia, Pa: JB Lippincott; 1995:594-606.

 
Previous
Next
 
Base of the skull computed tomography scan showing extensive fibrous dysplasia. Note the asymmetrical affectation, with near-total obliteration of various neural foramina at the base of the skull. This degree of fibrous dysplasia can result in multiple cranial nerve compression neuropathies, of which blindness and deafness (from involvement of cranial nerves II and VIII) are among the most disabling.
Café au lait spot. This is a fairly large, irregular-edged ("coast-of-Maine" variety) lesion. It presents as a brownish, otherwise-asymptomatic macule/patch. The degree of pigmentation is fairly uniform.
Fibrous dysplasia of a long bone characterized by focal bony expansion, patchy areas of sclerosis, and bony cyst formation.
This plain skull radiograph shows marked macrocrania, frontal bossing, and a markedly thickened bony table in patchy areas, particularly at the base of the skull and occiput. The skull also shows the hair-on-end appearance suggestive of Paget disease or poorly controlled hemoglobinopathy (eg, beta thalassemia, sickle cell disease).
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2012 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.