A 19-year-old man with a BMI of 23.8 kg/m2 (5 ft 7 in; 152 lbs) presented with the concern of 3 years of progressively enlarging head leading to an increase in hat size. The patient fulfilled the criteria for macrocephaly as his head circumference was 62 cm, which was above the 97th percentile for his age [1]. CT head revealed homogeneous bilateral hypertrophy of the temporalis, masseter, and medial pterygoid muscles with no evidence of a neoplastic process (Fig-1, Fig-2, and Fig-3). While genetic syndromes can be a cause of out-of-range head circumference, familial and environmental factors can contribute to variations [2,3]. In this case, the patient’s history revealed a history of bruxism since adolescence, however, no other physical or developmental abnormalities were noted. As a result, our case demonstrates bruxism and subsequent masticatory muscle hypertrophy as another possible cause of macrocephaly.

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