It has been a long while since I've posted one of the cases I've worked on and now its time to clear off my desk (before our CAP inspection).
The patient is an 83-year-old white man, non-smoker, who presented 2 months prior to surgery with cough and shortness-of-breath and was found to have a left lower lobe infiltrate and pleural effusion. After hospital admission and a course of antibiotics, the patient's symptoms initially improved. However, he returned again about one month later with the same symptoms and persistent infiltrate. Bronchoscopy revealed a mass-like lesion but cytologic studies were negative. He underwent CT-guided biopsy of the infiltrate which showed adenocarcinoma. He subsequently underwent lobectomy and that specimen showed three ill-defined mass-like areas of consolidation measuring, respectively, 7 cm, 5 cm and 3 cm each in greatest dimension. All three areas were extensively sampled (1 block for every cm of the largest dimension of the tumor) and all showed a similar histological appearance. Below is a typical area:
High-power view showing typical intranuclear inclusions:
Ancillary IHC stains were done to further characterize this tumor as mucinous vs. non-mucinous.
Mucin (above) and diastase-resistant PAS (below):
No areas showing definitive features of invasion were identified in any of the three gross areas of consolidation; however, given that none of these areas were submitted in their entirety, the most prudent diagnosis is adenocarcinoma with non-mucinous BAC features. From the dimensions of these areas that I provided above, submitting these lesions in their entirety would be impractical. Moreover, sections from grossly uninvolved areas between and adjacent to the gross areas of tumor also showed microscopic BAC. One subcarinal lymph node (station 7), 1 hilar (station 10) and 3 lobar (station 12) LNs were negative for metastatic adenocarcinoma.
My next post will continue discussion of BAC in the context of this case, incorporating data from recently published papers that I hope you'll find helpful in the diagnosis of these tumors.