Case 85

A 60-year-old female with a 2.1 cm right upper lobe mass.

1. What's your diagnosis?

   A: Reactive

   B: Sclerosing pneumocytoma

   C: Adenocarcinoma in situ

   D: Adenocarcinoma

Answer

The correct answer is D. Sections show lung parenchyma involved by a small focus of atypical glandular cells with pleomorphism and rare intranuclear inclusions.

• Cytologic features favoring adenocarcinoma (especially in lung):

  • Papillary or pseudopapillary formations

  • Acinar gland-like structures

  • 3D cell balls

  • Picket-fence or drunken-honeycomb appearance in mucinous tumors

• Documentation guidelines:

  • It is helpful to record adenocarcinoma patterns in small biopsies or cytology, but

  • Documenting relative percentages of patterns is not recommended (unlike resection specimens)

• Clinical significance:

  • Presence of solid and/or micropapillary patterns in core biopsies (e.g., from lung adenocarcinoma) is associated with poor prognosis, especially in settings like stereotactic body radiation therapy or thermal ablation therapy.

Reference: https://tumourclassification.iarc.who.int/chaptercontent/35/313

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD