PMC5203867_01
CT images of neck mass (a) demonstrating diffuse thyroid mass with tracheal luminal compression and left parotid mass (b) with central necrosis.
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CT images (Figure 1) revealed a diffuse thyroid mass extending substernally with tracheal luminal compression to 7 mm, a left necrotic 2.6 cm parotid mass extending into the deep lobe, multiple pulmonary nodules, a pancreatic head mass, and possible serosal implants along the transverse colon.
FNA of thyroid and parotid contained similar cytologic material with malignant cells arranged singly and in dyshesive groups in a necrotic background. A few background Hurthle cells are noted (a).
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Aspirate smears from thyroid and parotid masses appeared similar, composed of poorly differentiated cytologically malignant cells present in dyshesive groups and singly, having enlarged, vesicular nuclei with a thin rim of inconspicuous cytoplasm (Figures 2(a), 2(b), and 2(c)). Within the thyroid aspirate, several groups of more cohesive cells were noted with abundant eosinophilic granular cytoplasm and round, regular nuclei, consistent with Hurthle cells (Figure 2(a)).
Cell block contained malignant cells expressing pancytokeratin cytoplasmic immunoreactivity and PAX8 nuclear staining but stained negatively with B lymphocyte marker CD20.
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Cell block specimen from the parotid aspirate was quantitatively limited and contained cytologically malignant single cells in occasional aggregates remarkable for enlarged, vesicular nuclei with prominent nucleoli and scant cytoplasm in a necrotic background with red blood cells and scattered lymphoid cells (Figure 3(a)). TTF-1, CD20, and CD3 (Figures 3(b), 3(c), and 3(d)). The diagnosis of poorly differentiated malignant neoplasm, favor carcinoma, was rendered.
Isthmusectomy specimen demonstrates sheets of malignant cells displacing thyroid follicles; neoplasm is clearly pancytokeratin-negative with coexpression of PAX5 and polyclonal PAX8 immunoreactivity.
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Microscopic sections revealed thyroid, skeletal muscle, and adipose tissue extensively infiltrated by a high grade malignant neoplasm composed of mononuclear cells with atypical, round to ovoid nuclei, vesicular chromatin, and prominent nucleoli (Figure 4(a)). Malignant cells were immunoreactive with CD45, CD20, PAX5, and PAX8 but failed to express pancytokeratin, CAM5.2, chromogranin, or synaptophysin (Figures 4(b), 4(c), and 4(d)).