Melanosis Case Study

TITLE: BLADDER MELANOSIS: A RARE CASE REPORT

INTRODUCTION
Melanosis is defined as an abnormal deposit of melanin pigment in the tissues and was first described in 1986 [1]. It can be seen in any organ, but more often is described and characterized in oral mucosa and skin. Bladder melanosis (or melanosis vesicae) is an extremely rare condition and, so far, less than 20 cases have been reported in the literature, making its diagnosis difficult.
Here, we describe a new case, show our histopathological findings and discuss the fundamental criteria for making a correct diagnosis and recommend follow-up.
By many authors, it is considered to be a benign condition but its association with urothelial cell carcinoma of the bladder [2, 3] and melanoma [4] raises question about its truly benign condition and questions about the ideal follow-up.

The bladder is found to be dark brown or black in appearance and deposits can be found at any location in the bladder (Figure 1 and Figure 2). This dark colour can be due to melanosis, melanoma, haemosiderin or lipochrome deposits and these can be differentiated by histological examination.
Histopathological evaluation of bladder biopsies shows aggregates of pigmented granules within urothelial cells and/or similar granules within macrophages within the lamina propria [6].
Histologically, standard H&E staining does not reliably distinguish between melanin and other possible types of dark pigment, but staining of the granules is enhanced by Masson-Fontana stain or Schmorl’s reaction, and the pigmentation is abolished by bleach exposure. Pigmentation does not extend deeper than the lamina propria. Usually, Prussian blue and long Ziehl-Neelsen stains are negative, confirming that the pigmented granules are neither hemosiderin nor lipofuscin. These features support the notion that the granules are indeed melanin