[417] Diagnosis of Squamous Cell Carcinoma (SqCC) of Lung on Cytology Specimens in the Era of Novel Chemotherapeutic Agents

S Hu, M Fiel-Gan, S Mandavilli. Hartford Hospital, Hartford

Background: Advances in lung cancer therapy have included Bevacizumab or Pemetrexed in non-small cell lung carcinoma (NSCLC). Recent literature suggests both of these drugs not be used in SqCC, either due to reported complications or a lack of efficacy. FNA cytology or bronchial wash/brush specimens are commonly obtained specimens in lung tumors, but there is limited literature evaluating subtyping of NSCLC in this therapeutic context. The aim this study was to retrospectively examine the accuracy of cytology diagnosis of SqCC/ recognizing squamous component in NSCLC.
Design: Lung tumors with a diagnosis of SqCC or NSCLC with a squamous component on resected lung specimens or on tissue biopsies in which prior cytology was available were retrieved from the pathology files of a tertiary hospital from 2001-2009. Results of any immunocytochemical (ICC) stains performed on the cytology specimens were also summarized. The diagnosis on tissue specimens was considered the gold standard and compared to the prior cytology diagnosis.
Results: 130 surgical cases were retrieved including 116 cases of SqCC and 17 cases of carcinoma with a squamous component. 110 cases were diagnosed as malignancies on prior cytology as follows: SqCC 66 cases, NSCLC not otherwise specified 33 cases, NSCLC (non-squamous) 9 cases, and Small cell carcinoma (SmCC) 2 cases. 23 cases were non-diagnostic. ICC markers indicative of squamous differentiation (p63, or CK34BE12) performed in 2 cases were positive and both cases classified as SqCC. The cytological and histological diagnoses in the 11 cases of SqCC that were misclassified on cytology as non-squamous were listed in the following table 1.

Histological DxCytological DxCase Number
Basaloid SqCCSmall cell carcinoma2
Poorly differentiated SqCCMixed small cell/non-small cell carcinoma1
Poorly differentiated SqCCAdenocarcinoma3
Poorly differentiated SqCCPoorly differentiated adenocarcinoma1
Adenosquamous carcinomaAdenocarcinoma3
Moderately differentiated SqCCAdenocarcinoma1
Dx: diagnosis

Conclusions: Only 60.0% of SqCC were accurately recognized on cytology specimens. 30.0% of cases were categorized as NSCLC without further qualification. Additionally 10% of cases (mixed NSCLC, poorly differentiated SqCC and basaloid SqCC) can pose difficulties in subtyping SqCC. There is a lack of consensus of application of a panel of ICC on cytologic samples of NSCLC and this study warrants further investigation towards optimizing a panel of ICC stains in this era of newer therapeutic chemotherapeutic agents.
Category: Cytopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 50, Wednesday Afternoon


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