Case 45

A 85-year-old female with a right lower lobe lung mass.

1. What's the morphology impression of big category?

   A: Primary lung benign neoplasm

   B: Primary lung malignant neoplasm

   C: Metastatic malignancy

   D: Primary or metastatic carcinoma

   E: Primary or metastatic sarcoma

   
   

2. The tumor was found to be positive for stains below; while negative for pan-keratin, TTF-1.

   
   

   

   ER

   
   

   

   CD56

   
   

   

   CD99

   
   

   

   Inhibin

   
   

3. Based on the morphology and immunostains that are positive; What is the diagnosis?

   A: Well differentiated carcinoid

   B: Small cell carcinoma

   C: Desmoplastic small round cell tumor

   D: Metastatic carcinoma with sex cord differentiation

   E: Uterine tumors resembling ovarian sex cord tumors

   
   

Answer

References: https://tumourclassification.iarc.who.int/chaptercontent/34/248

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD