Contributed by Rebecca Leeman-Neill, MD, PhD and Walid Khalbuss, MD, PhD
The patient is a 58 year old woman with a 3.4 x 2.3 x 1.3 cm solid nodule with some small cystic spaces occupying the mid and lower left pole of the thyroid, as seen on ultrasound imaging (Figure 1A: longitudinal plane, 1B: transverse plane). The patient has noted an increase in size of this nodule and associated dysphagia. TSH and T3 are within normal limits. The patient also has a history of low-grade lymphoma diagnosed 8 years ago, after presenting with cervical lymphadenopathy, for which she has received intravenous immunoglobulin (IVIG) treatments.
The thyroid fine needle aspirate smears are cellular with a pattern dominated by a monotonous population of small lymphocytes, the majority of which are slightly larger than a normal lymphocyte, with minimal cytoplasm and a mildly atypical appearance. The nuclei are round, regular or slightly irregular with coarse clumped and regular chromatin, as well as inconspicuous small nucleoli (Figures 2, DQ-stained smears (10X), 3, DQ-stained smears (20X), 4, DQ-stained smears (40X), 5, DQ-stained smears (40X) and 6, Pap-stained smear, (40X)). The chromatin appears dense and coarse on the Pap stain (Figure 6). The larger cells, resembling immunoblasts, are of medium size and show dispersed, vesicular chromatin, dense blue cytoplasm, and a visible small central nucleolus (Figures 4 and 5). No histiocytes or tingible-body macrophages are seen. No mast cells are present. These features are highly suspicious for chronic lymphocytic leukemia/ small lymphocytic lymphoma (CLL/SLL). Therefore, specimens were collected for flow cytometric studies, for cell block, and two air-dried smears were prepared for FISH testing during on-site evaluation.