p40 in metastatic pulmonary trophoblastic tumour: potential diagnostic pitfall on histopathology
- Author:
Archana George Vallonthaiel
;
Ritika Walia
;
Raja Pramanik
;
MC Sharma
;
Deepali Jain
- Publication Type:Case Report
- Keywords:
p40;
immunohistochemistry;
trophoblastic tumours;
lung metastases
- From:The Malaysian Journal of Pathology
2017;39(2):175-179
- CountryMalaysia
- Language:English
-
Abstract:
p40, one of the two isomers of p63, is nowadays widely used for diagnosis of squamous cell
carcinoma, especially in subtyping non-small cell carcinoma on lung biopsies. We describe a case
in which lung tumour was misdiagnosed as squamous cell carcinoma due to p40 immunopositivity.
A 36-year-old lady presented with cough and left sided chest pain of 2 months duration. Chest
imaging revealed a lesion in left lower lobe of the lung and biopsy was suggestive of squamous
cell carcinoma. However, past history revealed amputation of great toe for non-healing discharging
ulcer which on histopathology was diagnosed as choriocarcinoma. She also had a history of
hysterectomy five years ago, details of which were not available. Post-amputation β-hCG levels
were high and she had been treated with multimodality chemotherapy for choriocarcinoma. She
had good response to chemotherapy initially, however became resistant later on. Review of the
lung biopsy in the light of the past history along with extensive literature review led to the final
diagnosis of metastatic trophoblastic tumour to lung. Hence, awareness that p40 immunopositivity
can be seen in trophoblastic tumours is essential to avoid misdiagnosis, especially in sites like the
lung where squamous cell carcinoma is common.
