To the Editor.—Papillary carcinoma is by far the most common malignant tumor of the thyroid gland, in part because its recognizable morphologic spectrum has enlarged considerably in recent years. From being simply de-. fined as "a malignant thyroid tumour containing papillary structures,"1(p22) it has mushroomed into a multitude of variants based on a combination of architectural, cytoplasmic, and nuclear features. One of these, known as the encapsulated follicular variant,2 is particularly treacherous because its follicular architecture and well-differentiated nature results in a marked similarity with a follicular adenoma when it is encapsulated and with a hyperplastic nodule when it is not. As currently agreed, the inclusion of this lesion into the papillary carcinoma family is largely dependent on the presence of a set of nuclear features, which include overlapping, clearing, semilunar shapes, longitudinal grooves, and pseudoinclusions (herein referred to as "papillary thyroid carcinoma (PTC) type"). Alas, these features may be not immediately apparent, and may be missed altogether. In this paper we call the reader's attention to a feature that may be present in these lesions and that—if properly identified—constitutes an important clue to the fact that the lesion in question does indeed belong to the papillary carcinoma family. We have referred to it colloquially over the years as the "sprinkling" sign, because of the impression one gets when looking at the lesion on very low power, which is that of somebody having grasped a handful of minute neoplastic follicles from a bag and sprinkled them into an apparently benign follicular nodule.
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