Cellular Blue Nevus Diagnosed following Excision of Melanoma: A Challenge in Diagnosis

Abstract

A case of a 41-year-old woman with a history of nodular melanoma (NM), associated with an indurated dome-shaped blue-black nodule with a diameter of 1.2 cm in the gluteal region, is presented. Clinical diagnosis of the lesion, present from birth, was blue nevus. Recently, the nodule has been showing a mild enlargement and thus complete resection was performed. Histological analysis revealed a pigmented lesion with an expansive pattern of extension into the dermis and the subcutaneous adipose tissue. The lesion displayed an alveolar pattern as well as a pigmented dendritic cell pattern. The histology was consistent with cellular blue nevus (CBN); however, the history of NM which was excised one year earlier, as well as the clinical information about the slow growing lesion, included a differential diagnosis of CBN, borderline melanocytic tumor, and malignant blue nevus. Additional immunohistochemical (HMB-45, p16, and Ki-67) and molecular (BRAF V600E mutation) analyses were performed on both lesions: the CBN-like and the previously excised NM. Along with lesion history and histological analyses, p16 staining and BRAF were useful diagnostic tools for confirming the benign nature of CBN in this case.

Nevus Blue as a Sporadic Finding in a Patient with a Blue Toe?

“…The frequency of malignant transformation of blue nevi is between 5.2 and 6.3% [ 6 ]. No consensus has yet been reached on the histological features indicating malignancy in blue nevi, and this poses significant diagnostic difficulties in attempting to distinguish between benign and malignant blue nevus [ 7 ]. The presence of irregular edges with satellites (satellitosis) is considered a strong precondition for malignancy [ 5 ].…”

“…The presence of irregular edges with satellites (satellitosis) is considered a strong precondition for malignancy [ 5 ]. Other signs considered to be indicative of possible malignant transformation are infiltration boundaries, common mitoses, nuclear pleomorphism, hyperchromasia [ 7 ]. According to many authors, the most important histopathological sign distinguishing benign and malignant blue nevi is the widespread necrosis [ 7 ].…”

“…Any case of increasing and extending blue nevus boundaries is a major indication of their surgical removal [ 7 ] [ 11 ]. The excision should be through a technique leading to complete elimination of the lesion and should ensure compliance with the boundaries of surgical security [ 22 ].…”

Histologic mimics of malignant melanoma

“…(20) There is a lot of confusion and controversy around this term, with no consensus regarding the classification for CBN, atypical CBN and malignant blue nevus. (22,23) Malignant blue nevus is an aggressive form of melanoma that typically arises in the background of a blue nevus or CBN, and is associated with metastasis and death. This tumour is more commonly seen on the scalp and in older patients, and it has a slight male predominance.…”

Oral squamous cell carcinoma involving a blue cell nevus in the palate

“…However, there are no reports demonstrating involvement of OSCC with benign neoplasms of melanocytic origin, such as blue cell nevus, which is a benign melanocytic lesion shown mainly in women, with the palate being the most affected anatomic site in the oral cavity, exhibiting variation from a blue to blackened color 11 . Histopathologically, blue cell nevus exhibits fusiform cells disposed parallel to the epithelial tissue, exhibiting a brownish cytoplasmic pigmentation similar to that of melanin 12 .…”