Endocrine Complications in an Adolescent with Fibrous Dysplasia

Case Report

J Pediatri Endocrinol. 2023; 8(1): 1060.

Endocrine Complications in an Adolescent with Fibrous Dysplasia

Look SE*; Timme K

Department of Pediatrics, University of Utah, USA

*Corresponding author: Look, SE Department of Pediatrics, University of Utah, 81 N Mario Capecchi Dr, Salt Lake City, UT 84113, USA. Tel: 239-699-2406 Email: sydney.look@hsc.utah.edu

Received: September 28, 2023 Accepted: October 20, 2023 Published: October 27, 2023

Abstract

McCune Albright Syndrome is characterized by the triad of fibrous dysplasia, cutaneous manifestations, and endocrine dysfunction. While this disease is typically associated with precocious puberty, there are other endocrinopathies to consider. An adolescent with fibrous dysplasia was diagnosed with acromegaly, hyperthyroidism, phosphate wasting, and hypogonadotropic hypogonadism. His course was complicated by optic neuropathy and parasellar mass ultimately determined to be due to progression of skull base fibrous dysplasia. There was additional consideration of side effects from octreotide. This case exemplifies the potential for under-recognition of acromegaly in McCune Albright Syndrome, which can be associated with cranial nerve deficits. Fibrous dysplasia progression may be associated with additional endocrine dysfunction depending on the location, with potential for necrosis or structural damage of the pituitary gland. Physicians should have high suspicion for endocrinopathies with low threshold for evaluation to optimize outcomes in this population.

Keywords: Acromegaly; McCune albright syndrome; Optic neuropathy; Octreotide

Abbreviations: MAS: McCune Albright Syndrome; FD: Fibrous Dysplasia; GNAS1: Guanine Nucleotide Binding Protein, Alpha Stimulating Activity Polypeptide-1; GH: Growth Hormone; IGF-1: Insulin-Like Growth Factor-1; NR: Normal Range; TSH: Thyroid Stimulating Hormone; T4: Tyroxine; T3: Triiodothyronine; LH: Luteinizing Hormone; FSH: Follicle-Stimulating Hormone; MRI: Magnetic Resonance Imaging

Introduction

MAS is characterized by FD, cutaneous manifestations including café-au-lait macules, and endocrine dysfunction. MAS occurs due to a mosaic GNAS1 gene mutation with a variety of clinical effects [1-4]. There are multiple endocrinopathies in MAS, though GNAS1 mutations are typically associated with endocrine hyperfunction with precocious puberty as one of the more common manifestations. Acromegaly is also common in MAS (20-30%) with an association in patients with skull base lesions [3,5,6].

Acromegaly is caused by excess GH production from the pituitary gland, which stimulates IGF-1 and promotes rapid dysregulated physical growth. GH excess in childhood, known as gigantism, results in late closure of epiphyses, often manifesting as tall stature. Acromegaly occurs after growth plates fuse and results in coarse facial features and gradual enlargement of hands and feet along with systemic effects. While acromegaly is often caused by a GH-secreting pituitary adenoma, it can also occur due to diffuse somatotroph hyperplasia as part of a genetic syndrome [6,7]. Medical treatment occurs if transsphenoidal surgery is ineffective or contraindicated. Medications include somatostatin analogues that inhibit GH secretion such as octreotide (injection or oral formulation), GH receptor antagonists, and rarely dopamine antagonists.

Case Presentation

A 17-year-old male with FD was referred to pediatric endocrinology for evaluation of abnormal thyroid function noted during an emergency department visit for fatigue and palpitations. His exam was remarkable for tall stature, macrocephaly, coarse facial features, and large hands and feet.

He fractured his right femur at age 5 leading to diagnosis of FD. He has a limb length discrepancy and uses crutches and a wheelchair for mobility. He has scoliosis and an acquired Chiari 1 malformation. He reported normal pubertal timing with exam consistent with pubertal stage 5. He had hyperpigmentation on his back determined to be reaction to surgical tape but no distinct café au lait macules. His height was 6 feet 1.8 inches (187.4cm), while his sex-adjusted mid-parental height was 5 feet 10 inches (178cm) (Figure 1). In comparison, his actual height was greater than 2 standard deviations above his anticipated adult height.

Citation: Look SE, Timme K. Endocrine Complications in an Adolescent with Fibrous Dysplasia. J Pediatri Endocrinol. 2023; 8(1): 1060.