Endocrine Abstracts

Background: Anti-synthetase syndrome (ASS) is an idiopathic inflammatory myopathy (IIM). Clinical features may include myositis, interstitial lung disease (ILD), non-erosive arthritis, Raynaud’s phenomenon, and mechanic’s hands with the presence of anti-synthetase antibodies. Although ASS-neoplasia association has been reported, it remains scarce and debated association. Herein, we report an original case of thyroid carcinoma in a patient followed for ASS.

Case report: A 40-year-old woman, consults for myalgia and weakness of the 4 limbs since 4 months. She presented with progressive proximal muscle deficit, elevated muscle enzymes, mechanics’ hands, ILD and positive anti-JO1 antibodies, thus she was diagnosed with ASS. Treatment was based on corticosteroids and Cyclophosphamide with good evolution. Initial screening for neoplasia was negative. Six years later, during a routine check-up, examination found a centimetric thyroid nodule. Thyroid function test was normal. Cervical ultrasound showed a 7mm right lobar thyroid nodule classified as EU-TIRADS 5. Fine needle aspiration found cytological atypia of undetermined significance. Total thyroidectomy was performed. Pathological examination concluded that a non-encapsulated intrathyroid papillary carcinoma. In addition to the surgical treatment, the patient received radioactive iodine with good outcome. The current follow-up is 2 year.

Discussion: We report the occurrence of thyroid neoplasia in a patient diagnosed with IIM, after 6 years of follow-up. The originality of this case is due to of the type of the IIM and the delay in the onset of the cancer in relation to its diagnosis. Compared to other IIM, ASS’ association to neoplasia is still debated: in the cohort of Pinal-Fernández, with 169 ASS patients, the frequency of cancer doesn’t seem higher than that of the general population. The Chinese cohort of Shi, with 124 ASS patients, found that 6.5% developed neoplasms, with a mean time of 3 years between neoplasia and SAS, of which, the majority presented with ILD. In the review carried out by Boleto, male gender, age over 60 years, and the presence of anti-SSA/Ro were predictive factors of development of cancer in ASS patients.

Conclusion: Thyroid carcinoma was discovered in our observation during regular screening for ASS-associated neoplasia. Thyroid carcinoma-ASS is an extremely rare but possible association, which will need to be detected and treated. Given the rarity of ASS, recommendations regarding the systematic screening for cancer have yet been established. In the meantime, we must remain vigilant about the possibility of the occurrence of cancer in these patients, and therefore ensure regular screening.