A 15-year-old female presented with multiple, painless enlargement of the cervical and submandibular lymph nodes along with thyromegaly and fever since three months. She was initially diagnosed outside as having tuberculosis and was under antituberculous treatment since two months, to which there was no response. Routine laboratory investigations revealed hemoglobin of 10 gm%, erythrocyte sedimentation rate of 90 mm at the end of first hour, total leukocyte count of 14,600 cells/mm3 and a differential count of neutrophils-44%, lymphocytes-52%, monocytes-2%, eosinophils-2%.
Clinical diagnosis given was thyroid malignancy with metastasis. Ultrasound scan diagnosis was papillary carcinoma thyroid with cystic change and lymph nodal metastasis.
Fine needle aspiration cytology (FNAC) was performed from the thyroid as well as the lymph nodes. Smears were stained with Giemsa as well as hematoxylin and eosin and found to be richly cellular [Figure 1]. Smears from both the lesions, that is, thyroid and lymph nodes showed a similar cytomorphological picture. Microscopic examination revealed the presence of histiocytes with single to multiple nuclei, fine nuclear chromatin and inconspicuous-to-prominent nucleoli; no nuclear grooving or atypia was noted. The histiocytes had abundant pale cytoplasm containing numerous intact lymphocytes (emperipolesis) [Figure 1 lower inset], plasma cells and neutrophils [Figure 1 upper inset]. The background showed plenty of mature lymphocytes, plasma cells, and neutrophils. Based on this characteristic cytomorphology, a diagnosis of Rosai-Dorfman disease, nodal and extranodal, involving the thyroid, was made, ruling out malignancy. A subsequent histological examination of the lymph node biopsy confirmed the cytological diagnosis. The patient was treated with steroids with a good response and thus an unnecessary total thyroidectomy was prevented.