Ann Diagn Pathol. 2019 Apr 24;41:43-50. doi: 10.1016/j.anndiagpath.2019.04.008. [Epub ahead of print]

Micropapillary adenocarcinoma of lung: Morphological criteria and diagnostic reproducibility among pulmonary pathologists.

Monroig-Bosque PDC1, Morales-Rosado JA2, Roden AC3, Churg A4, Barrios R1, Cagle P1, Ge Y1, Allen TC5, Smith ML3, Larsen BT3, Sholl LM6, Beasley MB7, Borczuk A8, Raparia K9, Ayala A1, Tazelaar HD10, Miller R1, Kalhor N11, Moran CA12, Ro JY13.

Author information

1

Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Weill Medical College of Cornell University, Houston, TX, USA.

2

Health Sciences Research Department, Mayo Clinic, Rochester, MN, USA.

3

Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.

4

Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.

5

Department of Pathology, The University of Mississippi Medical Center, MS, USA.

6

Department of Pathology, Harvard Medical School, Boston, MA, USA; Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.

7

Department of Anatomic Pathology, The Mount Sinai Hospital, New York, NY, USA.

8

Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY, USA.

9

Kaiser Permanente, Santa Clara Medical Center and Medical Offices, Santa Clara, CA, USA.

10

Department of Pathology, Mayo Clinic, Phoenix, AZ, USA.

11

Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

12

Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Weill Medical College of Cornell University, Houston, TX, USA; Health Sciences Research Department, Mayo Clinic, Rochester, MN, USA.

13

Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Weill Medical College of Cornell University, Houston, TX, USA. Electronic address: JaeRo@houstonmethodist.org.

Abstract

CONTEXT:

Invasive micropapillary adenocarcinoma (MPC) is an aggressive variant of lung adenocarcinoma, frequently manifesting with advanced stage lymph node metastasis and decreased survival.

OBJECTIVE:

Identification of this morphology is important, as it is strongly correlated with poor prognosis regardless of the amount of MPC component. To date, no study has investigated the morphological criteria used to objectively diagnose it.

DESIGN:

Herein, we selected 30 cases of potential MPC of lung, and distributed 2 digital images per case among 15 pulmonary pathology experts. Reviewers were requested to diagnostically interpret, assign the percentage of MPC component, and record the morphological features they identified. The noted features included: columnar cells, elongated slender cell nests, extensive stromal retraction, lumen formation with internal epithelial tufting, epithelial signet ring-like forms, intracytoplasmic vacuolization, multiple nests in the same alveolar space, back-to-back lacunar spaces, epithelial nest anastomosis, marked pleomorphism, peripherally oriented nuclei, randomly distributed nuclei, small/medium/large tumor nest size, fibrovascular cores, and spread through air-spaces (STAS).

RESULTS:

Cluster analysis revealed three subgroups with the following diagnoses: "MPC", "combined papillary and MPC", and "others". The subgroups correlated with the reported median percentage of MPC. Intracytoplasmic vacuolization, epithelial nest anastomosis/confluence, multiple nests in the same alveolar space, and small/medium tumor nest size were the most common criteria identified in the cases diagnosed as MPC. Peripherally oriented nuclei and epithelial signet ring-like forms were frequently identified in both the "MPC" and "combined papillary and MPC" groups.

CONCLUSIONS:

Our study provides objective diagnostic criteria to diagnose MPC of lung.