Cytology features are suggestive adenoid cystic type carcinoma in thyroid gland (TBSRTC category IV)
- high cellularity, adequate for assessment
- most of the architecture pattern is cribriform type
- Few microfollicles structures and frequent globules are seen
- Occasional trabecular structures are seen
- Cells are round to ovoid with fine granular chromatin, and indistinct nucleoli, and scanty cytoplasm, arranged around variable size of spherical hyaline globules
- Definite features of papillary thyroid carcinoma (PTC): intranuclear inclusion and grooves are not seen
Practical Points of pathoclinics:
- This patient is a smoker and present with relatively rapidly progressive dyspnea along with ultrasound features of lower right side neck mass from which thyroid mass cannot be seen separately. Considering the clinical and radiological findings, present morphology more likely to arise from deeper structures like larynx and trachea, with secondary extension in the thyroid. This patients had normal salivary glands on radiology.
- Features of papillary thyroid carcinoma (intranuclear inclusion and grooves are not seen) should be seen to consider this case as a primary adenoid cystic type carcinoma of papillary thyroid carcinoma. Presence of only follicles doesn’t indicates the PTC in present case.
- TTF1 and thyroglobulin is useful in identification of thyroid origin.
- Thyroglobulin is comes negative in hyaline globules
- Direct extension and metastasis of adenoid cystic carcinoma from salivary gland and lung elsewhere is common than primary adenoid cystic type features in PTC.
- This type of unusual pattern is also seen in poorly differentiated thyroid carcinoma.
Mandal S, Jain S. Adenoid cystic pattern in follicular variant of papillary thyroid carcinoma: a report of four cases. Cytopathology. 2010 Apr;21(2):93-6. doi: 10.1111/j.1365-2303.2009.00654.x. Epub 2009 May 14. PMID: 19456847.
Baloch ZW, Segal JP, Livolsi VA. Unique growth pattern in papillary carcinoma of the thyroid gland mimicking adenoid cystic carcinoma. Endocr Pathol. 2011 Dec;22(4):200-5. doi: 10.1007/s12022-011-9174-7. PMID: 21863325.