Should LSIL-H Be a Distinct Cytology Category? A Study on Frequency and Distribution of 40 HPV Genotypes in a Cohort of Underserved Women
Haijun Zhou, Mary R Schwartz, Debora Smith, Dina R Mody, Yimin Ge. The Methodist Hospital, Houston, TX; Weill Medical College of Cornell University, Houston, TX; Baylor College of Medicine, Houston, TX
Background: The Bethesda System (TBS 2001) for gynecologic cervical cytology reporting classifies squamous intraepithelial lesions (SIL) into low grade (LSIL) and high grade (HSIL) lesions. In clinical practice, an intermediate term LSIL-H has been used in a small percentage of LSIL cases with atypical squamous cells insufficient qualitatively or quantitatively to diagnose HSIL. However, the diagnostic criteria of LSIL-H are not defined and little is known about HPV status in those patients. We therefore analyzed the frequency and distribution of 40 HPV genotypes among expanded cytology categories including LSIL-H.
Design: A total of 808 SurePath specimens were collected from women who were referred to our institution from 01/2000-4/2011 for abnormal Pap tests. The patients' average age was 36.5 years (range 19-85 yr). The cytologic interpretations included NILM (n=497), ASCUS (n=48), ASC-H (n=9), AGC (n=2), LSIL (n=165), LSIL-H (n=27), HSIL (n=56), adenocarcinoma (n=1) and unsatisfactory (n=3). HPV DNA was extracted from residual SurePath specimens and amplified with polymerase chain reaction (PCR) in the L1 region. HPV genotypes were determined by DNA microarray against 40 HPV subtypes followed by a confirmatory sequencing assay.
Results: Patients with LSIL-H had much higher frequency of high risk HPV (HR-HPV) infection (92%) than those with NILM (52%), ASCUS (72.9%), ASC-H (77.8%), LSIL (74.3%), or LSIL/ASC-H combined (74.4%). The frequency of HR-HPV infection in LSIL-H was strikingly close to that in HSIL (91.1%). HPV 16, the most common carcinogenic HPV type, was present in a much larger fraction of LSIL-H (36%) than in LSIL/ASC-H combined (13.8%), but in a smaller fraction than in HSIL (44.6%). Furthermore, LSIL-H and HSIL had similar fractions of low and intermediate risk HPV subtypes which were lower than in LSIL or LSIL/ASC-H combined. The HPV distribution patterns did not differ significantly between younger (<30 yr) and older (>=30 yr) age groups.
Conclusions: The patients classified as LSIL-H had a higher risk for HR-HPV infection which was similar to patients with HSIL and much higher than those with ASCUS, ASC-H, LSIL or LSIL/ASC-H combined. The differences were independent of patients' age. Recognizing LSIL-H as an independent diagnostic category may help in early identification of a higher risk subgroup in LSIL who may require a management algorithm comparable to HSIL.
Monday, March 19, 2012 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 64, Monday Morning