M 56

A round nodular density in RLL

Underlying pulmonary fibrosis (UIP)

A cellular tumor and underlying irregular fibrosis

Lymphangitic spread

Lymphangitic spread

Lymphatic tumor emboli

Pleural penetration

CD 56 TTF-1 C-Kit

Histologically poorly differentiated carcinoma, large cell, with neuroendocrine differentiation

Diagnosis: Poorly differentiated large cell neuroendocrine carcinoma in usual interstitial pneumonia