Transformation of cell type in uveal melanomas - A quantitative histologicanalysis

Objective: To describe the cytologic transformation and tumor progression i n a series of uveal melanomas. Methods: Fifteen cases of uveal melanoma, treated by primary transscleral l o cal resection without primary adjuvant treatment, needed enucleation beca use of local tumor recurrence. Cytologic and eel morphometric features of t he primary tumor and the intraocular recurrence were compared, with evaluat ion of the amounts of intermediate cells, epithelioid cells, mitotic figure s, and nucleolar area. Results: The cases were categorized into 2 groups, according to their cytol ogic characteristics. In the first group (5 cases), there was no cytopathol ogical transformation in the recurrent tumor. The nucleolar area was increa sed in only 1 case. In the second group (10 cases), the recurrent tumors sh owed transformation into a more epithelioid cell type. In all. but 1 case t here was an increase in epithelioid cells in the tumor recurrence. The nucl eolar area was increased significantly in all cases. The mean local recurre nce interval in all cases was 15.3 months, with no difference between the g roups. Death from metastases occurred in 7 cases in which the nucleolar are a was 4.2 mu m(2) in the primary tumor. Conclusions: These findings demonstrate that, in an individual tumor, the c ytologic phenotype can change considerably even after a relatively short ti me, resulting in an increase in tumor-related mortality. Clinical Relevance: Studies on the natural course of uveal melanoma have be en very limited and based purely on observations on the progression of mela nomas in terms of size and alteration of various clinical characteristics.