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A case report of papillary thyroid carcinoma dedifferentiated to squamous cell carcinoma presenting as a lung metastasis: A potential diagnostic pitfall
Author(s) -
Gadde Ramya,
Tafe Laura J.,
Tsapakos Michael J.,
Liu Xiaoying
Publication year - 2020
Publication title -
diagnostic cytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.417
H-Index - 65
eISSN - 1097-0339
pISSN - 8755-1039
DOI - 10.1002/dc.24422
Subject(s) - medicine , pathology , thyroglobulin , thyroid carcinoma , thyroid , metastasis , lymph node , carcinoma , immunohistochemistry , lung , lymph , cancer
Papillary thyroid carcinoma (PTC) tall cell variant (TCV) with squamous dedifferentiation is a rare entity. We present a case of 90‐year‐old woman who initially had a 2.8 cm conventional PTC in right lobe of thyroid who, couple decades later, had metastatic dedifferentiated PTC to right neck lymph nodes level II and IV with tall cell features; to right level IV and V lymph nodes with tall cell and squamous components, which recently presented exclusively as squamous cell carcinoma (SCC) metastasizing to lung. The squamous component in the lymph node and SCC in the lung were both positive for squamous marker p63 and PTC markers TTF1, PAX‐8 and BRAF V600E while negative for thyroglobulin and p16. The papillary component was positive for TTF‐1, BRAF V600E and P63 (majority); negative for thyroglobulin and p16. Final diagnoses were rendered based on combination of cytological features and immunohistochemical profiles. This report highlights the utilization of current biomarkers to distinguish between metastatic dedifferentiated PTC with squamous features and primary lung SCC, as well as the importance of recognizing this rare entity.