When a Goitre is a Thyroid Lymphoma

Abstract

Primary thyroid lymphoma is a rare cause of both thyroid malignancy and extra-nodal lymphoma. It typically presents as a rapidly enlarging goitre with compressive symptoms. Histological analysis of a biopsy specimen is necessary to confirm the diagnosis. Awareness of this disease is important for early diagnosis and appropriate treatment. A 55-year-old man was admitted due to a 3-month history of cervical enlargement, facial and periorbital oedema and dyspnoea, apparently due to a superior vena cava syndrome. However, cervical ultrasound showed asymmetrical thyroid enlargement, lobulated contours and a hypoechogenic texture. A neck CT scan showed calibre reduction of the superior vena cava. The diagnosis of primary thyroid lymphoma was confirmed by open biopsy of the thyroid gland. The patient started treatment with rituximab with clinical improvement.

Learning points: Primary thyroid lymphoma is rare, accounting for less than 5% of thyroid malignancies and less than 2% of extra-nodal lymphomas, but should be suspected in the presence of a rapidly enlarging goitre.Fine needle aspiration biopsy is the initial technique of choice, but core needle biopsy or open surgical biopsy may be necessary to establish the diagnosis.Treatment and prognosis are dependent on accurate histological classification, with the disease generally treated successfully with chemotherapy.

Keywords: Cervical enlargement; extra-nodal lymphoma; primary thyroid lymphoma.

Figure 1

Neck CT scan showing densification of fat in the upper mediastinum, calibre reduction of the superior vena cava and fat densification in the plane of the carina

Figure 2

PET showing high-grade hypermetabolic lymphomatous disease, with supra-diaphragmatic lymph node involvement forming adenopathic conglomerates without cleavage planes with the thyroid