[389] Utility of Immunocytochemistry on Direct Smear Preparations in the Diagnosis of Effusions

Stewart M Knoepp, Jeremiah Placido, Kristina Fields, Dafydd Thomas, Michael H Roh. University of Michigan Medical School, Ann Arbor, MI

Background: Metastatic malignancy represents a common cause of effusions. Immunocytochemistry (ICC) is useful in confirming a diagnosis of malignancy and gaining insights into sites of origin. Cell blocks are commonly utilized for this purpose; nonetheless, it is not uncommon for the malignant cells to present as a minority population within the milieu of background mesothelial cells and histiocytes. In cases where the malignant cells are sparse, they may not be represented in cell blocks thereby precluding immunophenotypic characterization. Thus, we sought to investigate the utility of direct smear preparations as a platform for ICC in the diagnosis of effusions.
Design: Air-dried, unstained direct smears were prepared for 48 malignant effusions and 17 reactive effusions for comparison. ICC for the following markers was performed following brief formalin fixation and antigen retrieval: EMA, MOC-31, p63, TTF-1, Napsin-A, PAX8, CDX-2, and calretinin.
Results: The results of ICC for the malignant effusions are summarized in the table below.

ICC Results
Malignancy (# cases)Immunostain# Positive (%)
Mullerian ADC (n=15)EMA15 (100%)
 MOC-3115 (100%)
 PAX815 (100%)
Lung ADC (n=9)EMA9 (100%)
 MOC-319 (100%)
 Napsin-A7 (78%)
 TTF-16 (67%)
Pancreatic ADC (n=5)EMA3 (60%)
 MOC-315 (100%)
 CDX-23 (60%)
Gastric ADC (n=4)EMA3 (75%)
 MOC-314 (100%)
 CDX-21 (25%)
Breast ADC (n=4)EMA4 (100%)
 MOC-314 (100%)
Urothelial carcinoma (n=4)p633 (75%)
Mesothelioma (n=2)EMA2 (100%)
 MOC-311 (50%)
 Calretinin2 (100%)
Colorectal ADC (n=2)EMA1 (50%)
 MOC-312 (100%)
 CDX-22 (100%)
Lung squamous cell carcinoma (n=1)p631 (100%)
 Napsin-A0 (0%)
 TTF-10 (0%)
Papillary thyroid carcinoma (n=1)EMA1 (100%)
 MOC-311 (100%)
 PAX81 (100%)
 TTF-11 (100%)
Anaplastic thyroid carcinoma (n=1)EMA1 (100%)
 MOC-311 (100%)
 PAX81 (100%)
 TTF-10 (0%)
Abbreviations: ADC, adenocarcinoma

Overall, EMA and MOC-31 immunoreactivity was observed in the tumor cells in 91% and 98% of malignant effusions, respectively. EMA immunoreactivity was focally observed within the calretinin(+) mesothelial cell population in 2 (12%) of 17 reactive effusions. Immunostains for MOC-31, p63, TTF-1, Napsin-A, PAX8, and CDX-2 were negative in all 17 reactive effusions.
Conclusions: Direct smears represent an effective platform for the performance of ICC in the diagnosis of effusions. ICC for calretinin, p63, TTF-1 & Napsin-A, PAX8, and CDX-2 are especially helpful for confirming metastases from mesothelioma, urothelial cell carcinoma & squamous cell carcinoma, lung adenocarcinoma, Müllerian adenocarcinoma, and gastrointestinal/pancreaticobiliary adenocarcinoma, respectively.
Category: Cytopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 69, Tuesday Morning


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