Case Report
A 41 year-old Ivoirian woman, non-smoker, who has a history of a non-complicated type one diabetes, presented with GD, diagnosed in May 2018, with a clinical picture of weight loss and trembling. The initial biological tests showed an undetectable thyroid stimulating hormone (TSH) level, with high free thyroxine level (fT4) (31 pmol/L, N: 9.0-19.0 pmol/L), high free triiodothyronine (fT3) (11.8 pmol/L, N: 2.9-4.9 pmol/L), anti-thyrotropin receptor antibodies (TRAb) were positive at 54 IU/l (N: <1.74 IU/L), anti-thyroglobulin antibodies, and anti-thyroperoxidase antibodies were both negative. Alkaline phosphatase and bone turn-over markers were in the normal range excluding Paget’s disease. Ultrasound showed a homogeneous hyper vascularized goiter with a peak systolic velocity estimated at 78 cm/s (N: 15-30 cm/s) with no other significant anomalies. A treatment with carbimazole was introduced. In December, during follow-up, the patient presented with GO that has developed over few months with conjunctival redness, chemosis, tearing, bilateral eyelid swelling, right upper eyelid retraction, blurry vision without diplopia, and ocular and retro orbital pain. Clinical activity score (CAS) was 7/10 for both eyes. There was no optic nerve involvement. Due to the severity of her GO, she received a 10-week-course of high-dose IV GC pulses (six pulses of 750 mg in 30 days, followed by 7 pulses of 430 mg in about 45 days) to improve the GO, and to normalize her thyroid function test that remained uncontrolled despite high-doses of carbimazole. After the IV GC, clinical reassessment showed a mild to moderate improvement of the CAS of 4/10 in both eyes. TSH level remained undetectable, however fT4 and fT3 were normalized (10.4 and 4.6 pmol/l respectively). One month later, a total thyroidectomy was performed by the ENT team in May 2019, with no postoperative outcomes.
During the follow-up, the patient has signaled (August 2019) a frontal bone depression without any other symptoms or history of recent trauma. The frontal depression was left-sided, with no pain, tenderness, nor frontal paresthesia. The CT scan performed in November 2019 has showed a rounded lytic lesion of the frontal bone involving the walls of the frontal sinus, measuring 25 x 25 mm. The patient was then addressed to the ENT clinic, with a CT scan control after 3 months that showed an increase of the size of the lesion measuring 35 x 42 mm. Magnetic resonance imaging showed a single lytic lesion of the frontal bone left-sided with no intracranial invasion (Figure 1 ). This lesion was weakly hyper metabolic on the positron emission tomography (TEP) scan with a standardized uptake value (SUVmax) of 4.8.
A frontal bone biopsy was performed under local anesthesia. Histological examination showed remodeled bone trabeculae separated by a loose fibrous tissue containing numerous capillary vessels (Figure 2 ). Cytologic atypia, cell crowding, mitotic activity, and giant cells were not present. A diagnosis of intra-osseous hemangioma was established.