First described in 1985, diffuse sclerosing papillary carcinoma of the thyroid (DSPC) is a rare variant malignancy, recently reported to account for 0.8% of papillary thyroid carcinomas.1,2
Patients present with a diffuse goitre and are mostly clinically euthyroid, but can also be hypothyroid or hyperthyroid. It occurs most frequently in young females and may be mistaken clinically for benign disease particularly thyroiditis.3–5
Most patients have lymph node metastases at the time of diagnosis and lung metastases are common.3
Cerebral metastases have also been reported.6
The presence of several pathological characteristics is diagnostic: diffuse firm enlargement of the thyroid gland, scattered islands of papillary carcinoma, extensive lymphatic permeation and lymphocytic infiltration, squamous metaplasia, sclerosis and numerous psammoma bodies.7
Detection of abundant psammoma bodies on ultrasonography may provide pre-operative evidence of DSPC.4
This could facilitate improved surgical planning for a technically challenging thyroidectomy.
Early studies suggested that DSPC had a poorer prognosis than classical papillary carcinoma due to its aggressive nature with frequent lymph node and distant metastases at the time of presentation. It had also been reported that eradication required a more aggressive therapeutic approach.3
However, more recent studies suggest that DSPC patients have a similar prognosis and that the treatment should be that for classical papillary thyroid carcinoma i.e. radical surgery, radio-iodine ablation and/or external radiotherapy.2,8
There are potential pitfalls which may delay the diagnosis of DSPC. In this case, the clinical presentation, biochemical, serological and initial radiological findings were all indicative of benign pathology. FNA indicated malignancy leading to surgery demonstrating its importance in the diagnosis of DSPC. As metastases are frequently present it is therefore important to consider this rare malignancy when investigating a goitre in a young patient.