A 48-year-old man presents to the endocrinology clinic with progressive coarsening of facial features, increased shoe size by 2 sizes over 5 years, and a wedding ring that no longer fits. On examination, he demonstrates characteristic acromegalic facies with prominent supraorbital ridges, enlarged nose, thickened lips, and the feature marked **C** in the diagram. He also reports bifrontal headaches, excessive sweating, and recent-onset type 2 diabetes mellitus. MRI pituitary reveals a 1.4 cm macroadenoma with suprasellar extension. Which of the following best describes the skeletal pathology at the structure marked **C** and its clinical significance in acromegaly?
A. Maxillary protrusion with palatal vault narrowing — the primary cause of sleep apnea in acromegaly
B. Temporomandibular joint arthropathy with condylar remodeling — a late complication requiring surgical intervention
C. Prognathism with widened interdental spacing and dental malocclusion — the most specific skeletal feature of acromegalic facies on clinical inspection
D. Mandibular hyperplasia with anterior open bite — a consequence of excessive growth hormone but not specific to acromegaly
Explanation
Why option 1 is correct
Prognathism with widened interdental spacing (diastema) and dental malocclusion is the most specific and clinically recognizable skeletal feature of acromegalic facies on simple physical examination. The structure marked C — the prominent mandible with prognathism — is pathognomonic for acromegaly when combined with other facial features. This occurs due to excessive growth hormone stimulating mandibular bone growth and soft tissue proliferation. The widened interdental spacing and malocclusion are direct consequences of mandibular enlargement and are highly suggestive of the diagnosis. According to Williams Textbook of Endocrinology, prognathism is the most specific skeletal marker of acromegalic facies that clinicians can identify on inspection alone, making it a key diagnostic clue in suspected acromegaly.
Why each distractor is wrong
Option 2: While mandibular hyperplasia does occur in acromegaly, anterior open bite is not the characteristic dental finding. The question specifically asks about the feature marked C (prognathism), which presents with widened interdental spacing and malocclusion, not anterior open bite. This distractor conflates mandibular growth with a specific dental occlusion pattern that is not typical of acromegaly.
Option 3: Temporomandibular joint arthropathy and condylar remodeling are potential long-term complications of acromegaly, but they are not the primary or most specific feature of the structure marked C. These are secondary changes that develop over time and are not the hallmark skeletal finding used for clinical diagnosis.
Option 4: Maxillary protrusion with palatal vault narrowing is not the primary pathology at the mandible (structure C). While sleep apnea is a major complication of acromegaly, it results from macroglossia, soft tissue hypertrophy, and airway narrowing — not from maxillary changes. This distractor misidentifies the anatomical site of the anchor structure.
High-YieldNEET PG
Prognathism with dental malocclusion is the most specific skeletal feature of acromegalic facies and should immediately raise suspicion for growth hormone excess; it is more diagnostically specific than supraorbital ridges, nasal enlargement, or macroglossia alone.
Williams Textbook of Endocrinology, 14th Edition, Chapter 9: Pituitary Pathology — Acromegaly
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