I would like to give a couple of clues and hope to have more opinions. will reveal the result next week.

1. location: think about upper, mid and lower neck tissues around here

2. cytology: shape, pleomorphism, cytoplasm, mitoses or apoptosis (high or low grade)

3. growth pattern and stromal features: low power and view from far away (epithelial, mesenchymal, lymphoid etc).

甲状腺的？象恶性。

The clearness of these pictures are terrific, but the conclution of diagnosis is difficult to drawn.

 Final diagnosis: Carotid body tumor (paraganglioma)

-Location: Surgeon don't know or don't tell you it is in the bifurcation of common carotid artery. Another common pitfall in upper neck is the salivary gland tumor mass mimicking squamous carcinoma 

-Cytology: Very helpful; it has neuroendocrine features, bland but can have pleomorphism

-Growth: Some can be sclerotic, simulating invasive carcinoma

Hope you enjoy the case.