Coexistence of diffuse large B-cell lymphoma and papillary thyroid carcinoma in a patient affected by Hashimoto's thyroiditis

SUMMARY Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. On the contrary, primary thyroid lymphoma (PTL) is a rare disease, accounting for 2% to 5% of all thyroid malignancies. Despite several cases in which both PTC and PTL arise in the setting of Hashimoto's thyroiditis (HT), the coexistence of both tumors in HT patients is very rare. Herein we report the case of a 66-year-old woman with long-standing nodular HT under replacement therapy, who presented with a fast, painless enlargement in the right anterior side of the neck. Thyroid ultrasonography demonstrated increased growth of a hypoechoic nodule in the right lobe measuring 32 × 20 mm. A total thyroidectomy was performed, and histology revealed a diffuse large B-cell lymphoma (DLBCL) on a background of florid HT. Moreover, a unifocal papillary microcarcinoma, classical variant (7 mm, pT1aNxMx), was discovered. The patient was then treated with chemotherapy for the PTL, but she did not undergo radioactive iodine ablation treatment for the microPTC as per guidelines. Two years after surgery, the patient had no evidence of recurrence of either malignancy. This rare case highlights the importance of monitoring HT patients with nodular lesions, especially if they have long-standing disease. In addition, PTL should be considered for differential diagnosis in elder HT patients who present with sudden thyroid enlargement.

Carcinoma papilífero da tireoide associado à tireoidite de Hashimoto / Thyroid papillary carcinoma associated to Hashimoto's thyroiditis

Existe controvérsia na literatura quanto à associação entre Carcinoma Papilífero de Tireoide (CPT) e Tireoidite de Hashimoto (TH) e também quanto a qual seria a relação etiológica entre ambos. OBJETIVO: Determinar a proporção de casos de TH entre pacientes com CPT, correlacionando com aspectos histomorfológicos. MÉTODO: Foi realizado estudo retrospectivo de pacientes consecutivos submetidos à tireoidectomia parcial ou total por CPT, entre 2007 e 2009, totalizando de 41 casos. RESULTADOS: Em relação à associação de TH e CPT, foram encontrados 11 casos (26,8%), sendo todos do sexo feminino, porém, sem significância estatística. Nos casos em que havia CPT coexistente com TH a idade média foi de 44,9 anos e sem a associação, 49,1 anos. O tamanho médio dos tumores entre os sem TH foi 20,53mm e os com TH foi de 12,72 mm - p = 0,4. Em relação ao estadiamento anatomopatológico, as proporções entre os que apresentam TH e os que não apresentam foram mantidas em T1a, T1b e T3. Em T2, não houve casos de coexistência entre TH e CPT. CONCLUSÃO: Há uma proporção de 26,8% de pacientes que possuem associação entre TH e CPT, porém, sem diferenças em relação ao tamanho do tumor.

There is controversy in the literature regarding the association between papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis (HT) and as to what would be the etiological relationship between them. OBJECTIVE: To establish the proportion of cases among patients with TH and CPT, correlating it with histomorphological aspects. METHOD: A retrospective study of patients undergoing partial or total thyroidectomy for PTC between 2007 and 2009, a total of 41 cases. RESULTS: Regarding the association of HT and CPT, we found 11 cases (26.8%), all females, but without statistical significance. The mean age was 44.9 years among the patients with coexistent TH and CPT, whereas it was 49.1 years without that association. The average size of tumors in those without TH was 20.53 mm and for those with TH it was 12.72 mm (p = 0.4). Regarding pathology staging, the ratiosbetween those with and those without TH were kept in T1a, T1b and T3. In T2, there were no cases of coexistence of HT and PTC. CONCLUSION: There is a rate of 26.8% of patients with association between TH and CPT, but without differences in relation to tumor size.