UPMC Case:

-- 59-year-old man, left chest wall/axilla mass, with history of chest wall  tumor,  US-guided FNA was performed.

 Thanks

 Additional informtion of Case 1:
The immunohistochemical studies show the neoplastic cells are positive for EMA, S-100, Vimentin, CK8/18 but negative for CK19.

What is the most possible diagnosis (please think out side the box)?

Some types of foreign body granuloma?

Parachordoma/myoepithelioma？

Mucinous Carcinoma？

弄成中文，供各位只看中文的老师指导。

59岁男性，左胸壁/腋窝肿物。曾有胸壁肿瘤病史。超声引导下行FNA

镜下如图

yang 老师提供补充信息如下

肿瘤细胞EMA, S-100, Vimentin, CK8/18 阳性，CK19阴性。

强子, thanks for your help. 

 The final diagnosis is parachordoma.

Parachordoma:

-- rare soft-tissue tumor resembling extraskeletal myxoid chondrosarcoma and chordoma

-- age from 7 to 62 years (mean, 35 years)

-- Sites: subfascial masses of the thigh, arm, chest wall, and buttocks 

-- Histopath: large, rounded eosinophilic cells embedded in a matrix that varied from myxoid to densely hyaline and multivacuolated (physaliferouslike)

 cells

-- Special stains: matrix stained with Alcian blue (ph2.0)

-- IHC: 

* strongly expressed CK 8/18, but not the others 

* also positive for: expressed EMA, S-100, and vimentin

-- D/Dx: 

* chordoma --> Positive for CK 8/18 (15 of 15) and CK 1/10

* extraskeletal myxoid chondrosarcoma --> consistently lacked CK