Report of a malignant melanoma arising in a small congenital nevus in a 3-year-old child.

Sir,

Malignant Melanoma (MM) is a rare pathology in childhood. The increased risk of developing melanoma in large congenital nevi is widely accepted, while risk of developing melanoma in small congenital nevi (SCN) is still a matter of controversy.[12] We report a case of melanoma arising in a SCN on right foot in a 3-year-old boy. The lesion was showing enlargement in last 6 months, from 3-4 mm in diameter to 1 cm [Figure 1]. After evaluation by the dermatologist (clinical and with epiluminescence microscopy) the lesion was excised and a broad resection with wide margin. Histopathology showed a melanocytic epithelioid and fusocellular proliferation with mitosis, ulceration and necrosis, leading to diagnosis of nodular MM of Clark level V and 7 mm thickness. Sentinel lymph node biopsy was positive and regional dissection showed micrometastases of a femoral node. No adjuvant treatment was used.[3] Follow-up at 3, 6, 12, and 36 months by blood tests and thoracic X-ray were negative.

Figure 1

Preoperative aspect of the lesion, showing a melanocytic nodule with signs of ulceration

The increased risk of developing a melanoma in giant and intermediate nevi is frequently reported. SCN are defined as having a diameter less than 1.5 cm.[45] Although rare, the occurrence of MM in small congenital nevi has been described either in adults or in children.[56] We could not find any report of MM arising from SCN in a child younger than 3 years of age. Some authors reported a high percentage of SCN to be associated with melanomas, thus concluding that these lesions may be considered as melanoma precursors.[5] Whether a small melanocytic lesion in a young infant is congenital or acquired soon after birth (tardive nevus) is sometimes difficult to ascertain.[1] Nonetheless, such lesions should be distinguished from melanoma, which may occur in early infancy and even congenitally. Due to the rarity of malignant melanoma in early ages, such a diagnosis may be delayed, leading to worse prognosis. In our case because of late surgical referral, 8 months after the first clinical signs of growth, lead to diagnosis at an advanced stage. Strict monitoring of these lesions by clinical and epiluminescence-based criteria is highly recommended.[5] Furthermore, the diagnosis of true SCN is sometimes difficult and the amount of associated risk is unclear, thus requiring further investigation on the nature and behavior of these lesions.

Our experience confirms that child melanoma can occur in SCN even in early age. Therefore, careful evaluation and monitoring of such lesions is essential, in order to perform prompt excision as clinical change appears.