Oxyphilic neoplasia can be caused by both environmental and genetic factors.

Mutations in the GRIM-19 gene, which encodes proteins that play an important role in cell metabolism, mayunderlie this form of thyroid cancer . Dysfunction of these proteins can lead to cell death, which affects the formation of oxyphilic neoplasia. Oxyphilic neoplasms result in oncocytic tumours, also known as Hürthle cell tumours.

These are tissue form ations consisting of thyroid follicle epithelial cells in which excess mitochondria accumulate and acidify the cytoplasm. Oncocytic tumours may occur singly or in clusters. They are localised within the thyroid gland. They may appear as primary lesions, but may also result from lymphocytic lesions of the thyroid gland (secondary lesions).

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Oxyphilic neoplasms may present as benign lesions; however, they may also be malignant. Malignant tumours can be diagnosed using histopathological methods. Benign lesions should not be underestimated as they can become malignant.

Benign forms:

• hürthle cell adenoma;
• oxyphilic nodule in nodular goiter;
• cluster of oncocytes in Hashimoto's goiter.

Malignant forms:

• oxyphilic carcinoma;
• oxyphilic form of papillary carcinoma.

Oxyphilictumours are of particular interest because of their polymorphism, the difficulty in differentiating between benign and malignant lesions, and consequently the choice of optimal therapy. Usually, patients with an oxyphilic tumour are referred by an endocrinologist for surgical treatment or radioactive iodine therapy.