An obstructing bronchial lesion

• Tissue fragments comprising basaloid cells surrounding balls of stromal material
  • Cells at periphery and not embedded within stromal material
• Cellular uniformity (important feature)
• Small cell size with high N:C ratio
• Oval to angulated nuclei
• Occasional distinct nucleoli
• Stippled to coarse nuclear chromatin

• Salivary gland-type tumours
  • Adenoid cystic carcinoma
  • Basal cell neoplasm
  • Myoepithelial neoplasm
  • Pleomorphic adenoma
• Small cell carcinoma
• Carcinoid tumour

 
A concurrent biopsy of the lesion was also performed.

• Cribriform islands and nests of relatively bland tumour cells
• Biphasic uniform epithelial (luminal) and myoepithelial (abluminal) cells
• Hyaline stromal material present in pseudolumina

 
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