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
- 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
Differential diagnoses
- Salivary gland-type tumours
- Adenoid cystic carcinoma
- Basal cell neoplasm
- Myoepithelial neoplasm
- Pleomorphic adenoma
- Small cell carcinoma
- Carcinoid tumour
Histologic findings
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
Diagnosis and discussion
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
- Clinical
- Similarities
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
