Challenging Case of Tall-Cell Variant of PTC Presenting as Benign Adenomatous Nodule

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 449-497-Thyroid Neoplasia & Case Reports
Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-460
Niyaz R Gosmanov1 and Albina K Gosmanova*2
1Oklahoma City VAMC, Oklahoma City, OK, 2Oklahoma Univ HSC, Edmond, OK
Background: Ultrasonpgraphic imaging (USI) has become a major tool assisting clinicians in determining degree of suspicion for malignant nodule, thus defining need for FNA versus surgical excision. When concerns for malignancy are not high, decision is frequently deferred to FNA accuracy of which had significantly improved in the last years, yet pathology reports might still omit some features which might be a result of limitations of FNA sampling, preservation of the sample or concurrent thyroid conditions downplaying concerns of malignancy.

Clinical case: 27 year old healthy Caucasian female presented in 2011 to Endocrinology clinic with a soft, palpable 3.9X2.4x1.9 cm nodule. USI revealed heterogenous nodule with no signs of calcifications, though some nodular vascularity was present; rate of growth on US was slow (less than 10% increase over 12 months period 4.3x2.4x1.8 cm). US-guided FNA biopsy of the most concerning area of the nodule was performed at the first encounter and results revealed benign adenomatous nodule with no concerning features ("macrofollicular clusters and flat sheets of cytologically bland follicular cells and back ground colloid"). Patient continued to be followed in the office with no changes in clinical status, thyroid function tests or USI. About 6 months ago patient decided to pursue removal of the nodule for cosmetic reasons and ENT consult was sought. Uneventful hemithyridectomy was performed and pathology report had unexpectedly shown tall-cell variant of papillary thyroid carcinoma (TC-PTC) confirmed on immunostain with no signs of vascular invasion. She is doing well clinically and is awaiting whole body RAI scan testing.

Conclusion: this case demonstrates challenges identifying thyroid cancer which might present with less defined pathological features and misdiagnosed as a benign nodule based on FNA alone with potentially serious consequences. While more common challenge is misdaignosing benign nodules as malignant ones, especially PTC, the other way around is encountered less often, yet might be much more consequential. Further studies to identify ways of reducing rates of misdiagnosis are needed and have to include detailed clinical history, presentation, USI apperance and potentially more extensive use of immunocytochemistry. Certain factors, like vascularity, have to be re-evaluated and in certain cases might indicate need for re-biopsy.

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1. Carcangiu ML, Zampi G, Pupi A, et al. Papillary carcinoma of the thyroid: a clinico-pathologic study of 241 cases treated at the University of Florence, Italy. Cancer. 1985;55:805-828.  2. LiVolsi VA. Surgical Pathology of the Thyroid. Philadelphia, PA: Saunders; 1990. 3.  Cytologic and Architectural Mimics of Papillary Thyroid Carcinoma: Diagnostic Challenges in Fine-Needle Aspiration and Surgical Pathology Specimens Zubair W. Baloch, MD, PhD, and Virginia A. LiVolsi, MD  Am J Clin Pathol 2006;125(Suppl 1):S135-S144     

Nothing to Disclose: NRG, AKG

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