Clinicopathological Profile of Primary Hyperparathyroidism with Special Reference to Ki-67 Labelling Index.

Context: Primary hyperparathyroidism (PHPT) can occur due to a neoplastic process or hyperplasia. While the disease presentation is predominantly asymptomatic in developed countries, this is not the case yet in India. Differentiation of the type of lesion can only be done based on histomorphology but has its own challenges. Immunohistochemical markers like Ki-67 have been studied to aid in diagnosis but data on this is sparse from India. Aims: The aim of this study is to assess the clinical, biochemical and pathological profile of PHPT and to analyse the differences in immunohistochemical marker Ki-67 among the various lesions. Setting and Design: A descriptive study was carried out on 38 PHPT patients who were treated at our institute from January 2011 to March 2021. Materials and Methods: Post-surgery, the causative lesions were categorised as adenoma (31), hyperplasia (5) and carcinoma (2). Clinical, biochemical, radiological and histopathological features of all lesions were collected and analysed. Ki-67 proliferation index was calculated. The various parameters were compared across the three groups of lesions and correlated with Ki-67 index. Results: Out of 38 patients, 37 were symptomatic with skeletal symptoms being the most common followed by renal symptoms. There was no difference in clinical or biochemical parameters among the three types of lesions. Significant negative correlation was seen between serum iPTH and serum 25-OH Vitamin D levels (P0.006) The median Ki-67 index was found to be 0.40% in hyperplasia, 0.49% in adenoma and 5.84% in carcinoma. Conclusion: PHPT still presents as an overtly symptomatic disease in India. Diagnosis of the nature of lesion depends on the accurate application of morphological criteria. A high Ki-67 index was not found to be an absolute marker of carcinoma, as it was also seen in a small proportion of atypical adenomas.