Protein p16 Immunohistochemical Expression in Premalignant and Malignant Lesions in Cervical Histopathology Specimens and Its Clinical Impact

Nivedita, Suresh (2015) Protein p16 Immunohistochemical Expression in Premalignant and Malignant Lesions in Cervical Histopathology Specimens and Its Clinical Impact. Masters thesis, Christian Medical College, Vellore.


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OBJECTIVES: 1. To evaluate the diagnostic utility of p16 to differentiate between the premalignant and malignant squamous and glandular lesions of cervix. 2. To assess the utility of p16 to distinguish between benign and dysplastic lesions of cervix. 3. To assess the clinical impact of p16 expression on the disease outcome. 4. To assess the performance of cytology as a screening tool compared to histology. METHODS: 120 cervical biopsies (15 cases each of CIN 1, 2, 3 and squamous cell carcinoma, 22 cases of adenocarcinoma and 38 reactive cases) were studied and p16 immunohistochemistry were performed. Score out of 8 was given based on intensity and proportion of p16 expression. Corresponding cytological diagnoses were also evaluated. RESULTS: Sensitivity of p16 in CIN 1, 2, 3, squamous cell carcinoma, adenocarcinoma were found to be 73.7%, 93.3%, 93.3%, 100% and 95.4% respectively. Specificity of p16 in cervical squamous and glandular lesions was 85.7% and 80% respectively. p16 over expression also correlated with stage of tumour, lymph node metastasis, local and distant metastasis. Intensity of expression correlated better with lesion severity than proportion. It did not correlate with grade of the tumour. 15.7% of reactive epithelium showed patchy weak cytoplasmic positivity for p16. Cytology had sensitivity of 35.7%, 69.2% and 50% for low grade lesions, high grade lesions and glandular lesions respectively. The time taken for a dysplastic lesion to progress into a higher grade lesion was 16 months. Among the morphological parameters used to diagnose cervical dysplasia, mitotic count was found to be the only parameter which showed statistically significant difference among the subtypes. Koilocytosis was significantly associated with CIN 1 and CIN 2 but not with CIN 3. All the cases of koilocytosis were negative for p16. The most common presenting symptom was vaginal discharge in CINs and cervical growth in carcinoma. 15.8% of women with CIN 1 were referred for biopsy due to abnormality in Pap smear. CONCLUSION: p16 is a reliable marker to detect cervical dysplastic lesions. It can differentiate benign mimics from dysplastic lesions. Over expression of p16 is associated with higher stage of tumour, nodal and distant metastasis. Pap smear test alone has a low sensitivity for low grade lesions.

Item Type: Thesis (Masters)
Uncontrolled Keywords: p16 ; CIN ; Squamous cell carcinoma ; Adenocarcinoma ; glandular lesions ; Pap smear ; cytology.
Subjects: MEDICAL > Pathology
Depositing User: Punitha K
Date Deposited: 19 May 2018 15:16
Last Modified: 22 May 2018 18:17

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