[395] Nuclear Pseudo-Inclusions Are Rare, but Nuclear Grooves Are Nearly Always Present, in Cytopathology and Histopathology Material of Encapsulated Follicular Variant of Papillary Thyroid Carcinoma

Florence Loo, Andrew Schreiner, Theresa Scognamiglio, Syed Hoda, Rana Hoda. Weill Medical College of Cornell University, New York, NY

Background: Encapsulated Follicular Variant of Papillary Thyroid Carcinoma (EFV-PTC) can be diagnostically challenging in cytopathology as well as histopathology material; mainly because its nuclear features can often be focal and subtle; and remain, thus far, a diagnostic challenge.
Design: All archived histopathology slides from surgically-resected EFV-PTC cases (2006-2011) were retrieved. Diagnosis was confirmed (Mod Pathol 2011;24:S1-S9, Acta Cytol 2002;46:555-561). Corresponding fine needle aspiration (FNA) cytopathology preparations (Diff-Quik and/or Pap) were retrieved. Consensus review (2 observers) was undertaken of all histopathology and cytopathology material, particularly with regards to nuclear features.
Results: Table 1 shows the results of the nuclear features based on the aforementioned review.

Nuclear Features of EFV-PTC Cells in Cytopathology and Histopathology
 CytopathologyCytopathology Histopathology
Grooves19/20 (95%)20/20 (100%) *
Elongation19/20 (95%)20/20 (100%)
Overlap19/20 (95%)20/20 (100%)
Ground Glass18/20 (90%) **20/20 (100%)
Irregular Shape17/20 (85%)20/20 (100%)
Pseudo-inclusions02/20 (10%)01/20 (5%) ***
Note: Most features (except grooves, vide infra) were readily identifiable in most preparations. *: Nuclear grooves were diffusely present in 15/20 and only focally present on histopathology material in 5/20 (25%) cases. **: In general, Pap and Diff-Quik preparations were equivalent and similar with regards to nuclear findings, except for evaluation of “ground glass” nuclei (inherently problematic on Diff-Quik). Ground glass nuclei were also a less prominent feature in histopathology material ***: The only case of EFV-PTC which showed nuclear pseudo-inclusions in histopathology material displayed solid features of PTC as well. Data on control cases, and other pathological features (including cellularity, characteristics of follicles and colloid, etc.) were non-contributory and are not shown herein.


Conclusions: Based on this series of EFV-PTC cases, nuclear pseudo-inclusions are a rare finding in cytopathology (10%) and histopathology (5%) preparations; however, nuclear grooves are evident in 100% of cases (but this finding may be focal in histopathology material in a minority of cases).
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 65, Wednesday Afternoon

 

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