Figure 1

Table 1 Effusions cases with contradictory morphological impressions and finaldiagnoses, and immunoprofiles

Age/Sex

SITE CytopathologyMorphologicalImpression

Final Diagnosis PositiveImmunostains

NegativeImmunostains

44/M Peritonealimplant/Ascites

Adenocarcinoma Malignantmesothelioma

Calretinin,WT1,CK5/6, Glut1

MOC31,BerEP4,TTF-1,PAX8,CEA

67/M Pleuralfluid

Mesothelioma Adenocarcinoma MOC31,BerEP4, CK7

TTF-1,CK 5/6,WT1,Calretinin,D2-40,S100

92/F Pleuralfluid

MalignantNeoplasm

Reactivemacrophageandmesothelialcells

CD163,CK 5/6(focal),CK7,Calretinin,Vimentin

MOC31,BerEP4,TTF-1,CK20,Napsin,PAX8,Mucin,S100

74/F Ascites Malignant(MixedFeaturesAdenocarcinoma& Mesothelioma)

Adenocarcinoma Mucin,MOC31,CK7

CK20,PAX8,Wt1,CK5/6,ER,CA19-9

77/F Pericardialfluid

Malignant Reactivemacrophageandmesothelialcells

CD163, WT1 CK5/6,MOC31,BerEP4,TTF-1

60/F Pericardialfluid

Atypical Adenocarcinoma CK7,P53, CEA

CK20,ER, PAX8,TTF-1,Napsin,CAm5-2,CK5/6,WT1,Calretinin,MOC31,BerEP4,CD163

42/F Pleuralfluid

Mesothelioma Adenocarcinoma MOC31,BerEP4,and WT1

CK 5/6,calretinin,PAX-8,Ca 19.9,CD 163(stainshistiocytes),CEA(variable)

Abstracts S15

15

Utility of Flow Cytometry Analysis for Pleural Fluids

Maren Fuller, MD, Michael Thrall, MD. Houston Methodist Hospital,Houston, Texas

Introduction: Pleural fluid samples with many lymphocytes are commonlyreceived in the cytology laboratory. However, it is difficult to distinguishreactive lymphocytes from Non-Hodgkin’s Lymphoma (NHL) based onmorphology alone. Flow cytometry can be a useful test to identify NHL inpleural fluids, however literature on this subject is limited. We aim to addressthe utility of sending pleural fluid specimens for flow cytometry analysis.Materials and Methods: This study is a 5 year retrospective review of 325pleural fluid samples from 298 patients with corresponding flow cytometryanalysis. The flow cytometry results were correlated with the cytologicfindings and clinical data.Results: Of 4,158 pleural fluids received over 5 years, 325 (7.8%) hadcorresponding flow cytometry analysis. Of these 325 samples, 57 (17.5%)were positive for NHL/leukemia by flow cytometry. 45 samples hada known history of NHL/leukemia, and 33 (73.3%) were positive for NHL/leukemia by flow cytometry. The remaining 280 samples had no reportedhistory of NHL/leukemia, and 24 (8.7%) were positive by flow cytometry.Of the cytology reports for these 24 cases, 8 (33.3%) mentioned atypicalcells, and 9 (37.5%) were consistent with NHL or leukemia. The remainingcases describe a monotonous population of small lymphocytes.Conclusions: Flow cytometry analysis for pleural fluids is of littleutility, as we found only 8.7% of cases without known histories werepositive for NHL/leukemia. Of these positive cases, many had atypicalcells that suggested a diagnosis of hematologic malignancy. Conversely,in cases with a known history, 73.3% were positive for NHL/leukemia.Our study suggests that the utility of flow cytometry for pleural fluids islow except in cases with atypical cytologic features or known history.Future directions include identifying potential cytologic indicators tosuggest NHL in pleural fluids without atypical features or knownhistory.

16

Effusions Are Not Always What They Seem; Don’t Judge a Fluid by itsCover (Slip)

Tamar Brandler, MD, MS1, Melissa Klein, CT(ASCP)2, Oana Rafael, MD3,Mohamed Aziz, MD2. 1Hofstra North Shore-Long Island Jewish, New HydePark, New York; 2North Shore-Long Island Jewish Health System, Lake

Success, New York; 3North Shore LIJ - Lenox Hill Hospital, New York, NewYork

Introduction: Effusions may serve as the initial presentation of malignancy.A majority of malignant effusions are metastatic adenocarcinomas fromknown or unknown primary tumors. Evaluation of cytomorphologic featuresis the most important initial step in formulating a diagnosis, followed byutilizing immunohistochemical studies to finalize a proper diagnosis.Materials and Methods:We present seven fluid cases from different sites inwhich immunohistochemistry was critical to determine the accuratediagnoses and thus the proper course of treatment, despite conflictingcytomorphology (Table 1).Results: Four of the seven cases (two ascites and two pleural effusions)involved distinguishing between adenocarcinoma and mesothelioma; thecytomorphologic impression was contradicted by the immunoprofile. Threecases were determined to be adenocarcinoma after utilization of a fullimmunopanel, despite the classic mesothelioma intracellular windows, cellmicrovilli and skirts (Figures 1-3) (although morphologically one case hadmixed adenocarcinoma and mesothelioma features). The fourth caseappeared to form cell clusters, giving a glandular impression, with classicsmooth community borders; a full immunopanel and surgical follow-upconfirmed mesothelioma. Three of the seven cases (two pericardial and one

Figure 1

Figure 2

Figure 3

S16 Abstracts

pleural effusion) involved distinguishing between malignant and reactive/atypical processes. Two of these appeared to be morphologically malignantwith extremely large cells, high nuclear/cytoplasmic ratio, irregular nuclearmembranes, and hyperchromasia. These cases however proved to be merelyreactive histiocytes and reactive mesothelial cells upon immunohistochem-istry. The last case appeared to be nothing more than atypical cells butsubsequent immunohistochemistry confirmed adenocarcinoma.Conclusions: These cases epitomize the importance of immunostaining ineffusion specimens. An accurate diagnosis can be achieved only followinga complete panel of immunostains, especially in problematic cases. It isimportant to keep in mind that, despite our training in morphologicdiagnosis, immunostains can help guide us towards a correct diagnosiswhich will impact patient therapy.

17

Cytologic Diagnosis of Malignant Effusions: Adjunctive Use ofa Single Slide Dual CDX2/CK20 Immunohistochemical Stain toConfirm a Gastro-intestinal Primary

Marguerite Pinto, MD, Marcela Bertola-Rumeli, BS, HTL, QIHC.Bridgeport Hospital, Bridgeport, Connecticut

Introduction: The diagnosis of malignant effusions necessitates both thecytologic recognition of malignant cells and immunohistochemistry(IMH)to confirm a known primary or suggest a second primary. The sensitivity forcytologic diagnosis decreases when cancer cells are scanty often renderinga suspicious rather than a definitive diagnosis. CDX2 and CK20 are bothexpressed in carcinomas with intestinal differentiation most commonlycolorectal. We conducted a study to assess the use of a dual CDX2/CK20IMH in diagnosing malignant effusions from the GI tract where thediagnosis was confirmed by surgical pathology or suspected radiologically.Materials and Methods: Formalin -fixed paraffin embedded cell-blocks(CB) from 18 cytologically malignant effusions were tested with dual IMHon a single slide:CDX2 (EPR2764Y 1:200) and CK20 (KS 20.8 1;200),using high ph antigen retrieval and detection with Envision doublestainsystem in an autostainer .CDX2 nuclear stain was marked by DAB andCK20 by Permanent Red cytoplasmic stain.Appropriate external controlswere placed on each test slide.Primaries were Colon 8,Rectum 1, Appendix1, Stomach 7, Gall-Bladder 1; Signet Ring Carcinoma( SRC) 8; Moderatelydifferentiated (10).Cellularity of malignant cells varied from scant (7) tohigh (11).One patient had a history of Prostate Carcinoma but clinicallysuspected to have a second primary from colon.Results: Colon: CDX2 and CK20 dual strong positive 8/8 including SRC 3/3; Appendix (SRC) both negative; Stomach CDX2 positive 2/7(28%) CK204/7 (57%)including3/5 SRC; Gall Bladder CDX2 0/1:CK20 strong positive.The advantage of positive single or dual IMH was in locating even singlemalignant cells (SRC) in cases of low cellularity, thus confirming thecytologic diagnosis.Conclusion: A single Dual CDX2/CK20 IMH improves cytologic diagnosisof effusions by faciltating detection of single malignant cells in Colon SRCand 57% of stomach SRC when cellularity is low; confirming metastasesfrom a known primary and suggesting a second primary.

18

Incidence of Pneumocystis in HIV and Non-HIV ImmunocompromisedPatients

Mariam Mir, MD, Meghan Koch, DO, Haiying Zhang, MD,Carol Adair, MD. Baylor University Medical Center at Dallas, Dallas,Texas

Introduction: Pneumocystis jirovecii pneumonia (PJP) has long been asso-ciated with HIV positive patients with low CD4 counts but can also be seenin other immunocompromised patients. PJP in non-HIV patients may bemore severe, leading to a higher mortality rate as compared to HIV patients.The purpose of this study is to evaluate the distribution of PJP in HIV andnon-HIV patients in a large tertiary care hospital.