An obstructing bronchial lesion

Clinical history: A 46-year-old female, non-smoker, presented with shortness of breath. Imaging showed obstructive atelectasis and bronchoscopy revealed a 3.0 cm endobronchial submucosal lesion in the left main bronchus. Fine needle aspiration of the lesion was performed.

(Case contributed by: Dr Bibiana Tie, Princess Alexandra Hospital, Brisbane, Australia)

Cytologic findings

Differential diagnoses

Histologic findings

Diagnosis

Adenoid cystic carcinoma

It is particularly important to distinguish high grade/solid type adenoid cystic carcinoma from small cell carcinoma due to differences in treatment and prognosis
- Similarities
  - Occasional sheet-like architecture, seen especially in solid variant of adenoid cystic carcinoma
  - Small cell size and high N:C ratios
  - Stippled to coarse chromatin
  - Nuclear moulding
- Discriminating features which favour small cell carcinoma
  - Clinical
    - Significant smoking history
    - Higher propensity for nodal metastases
  - Cytomorphology
    - Greater nuclear pleomorphism
    - Lack of stromal fragments
    - Indistinct nucleoli
    - Occasional dirty / necrotic background
  - Immunohistochemistry
  - - Positive for TTF1 and neuroendocrine markers (synaptophysin and chromogranin A)
    - Negative for CD117 and does not demonstrate biphasic luminal/abluminal cell differentiation

Reference

Kim S, Chu J, Kim H, Han J. Comprehensive Cytomorphologic Analysis of Pulmonary Adenoid Cystic Carcinoma: Comparison to Small Cell Carcinoma and Non-pulmonary Adenoid Cystic Carcinoma. J Pathol Transl Med. 2015;49(6):511-519. doi:10.4132/jptm.2015.09.07

Case writer: Dr Noel Chia

Thoracic case 2

An obstructing bronchial lesion