Cellular blue naevus

Introduction

Blue naevi are seen usually on skin and rarely on oral mucosa, vagina or uterine cervix.[1] Three types of blue naevi known are: common blue naevus, cellular blue naevus and combined naevus which may be present at birth but usually appear around puberty.[2] Common blue naevi can occur on any site whereas cellular blue naevi are often seen on dorsa of hands, feet, buttock or face. Progressive growth is rare and rarely malignant transformation can occur in cellular blue naevus. Common blue naevi are seen as dome shaped, dark blue black papules and cellular blue naevi as dark blue black 1 to 3 cm nodules.[3] Histopathologically cellular blue naevi in addition to deeply pigmented dendritic melanocytes reveal cellular islands of closely aggregated, large spindle shaped cells with ovoid nuclei and abundant melanin may surround these islands.

Case Report

A 31-year-old man developed extensive yellow to orange papulo- nodular lesions on extensors of limbs and buttocks since one and half months. He was diagnosed as a case of xanthomatosis and investigations confirmed that he also suffered from diabetes mellitus and also had abnormal lipidogram. In addition he had one asymptomatic, non-progressive, deep dark blue, well-defined, smooth, shiny, dome-shaped, polygonal, 1.5x2 cm nodule on dorsum of right hand since 12-14 years. There was peripheral rim of normal skin which was encircled by a well-defined blue dotted line [Figure - 1].

Histopathology revealed some dendritic, wavy melanocytes filled with melanin and, prominent islands of spindle cells with abundant cytoplasm and associated densely pigmented melanophages in dermis and was consistent with diagnosis of cellular blue naevus.

Discussion

Clinically possibility of cellular blue naevus was kept, as nodule was 2X1.5 cm in size. Peripheral dotted blue line was unusual and during biopsy it was observed that naevus cells were infiltrating the dermis and subcutaneous issue upto that dotted line.

Naevus consisted of dark blue, friable, vascular tissue and complete excision was difficult. Clinical diagnosis was confirmed histopathologically as both wavy dendritic melanin filled cells and islands of spindle cells with ample pale cytoplasm were seen. Probably diabetes and xanthomatosis were chance associations and patient visited the department for them.