Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 52, Num. 1, 2004, pp. 127-127

Neurology India, Vol. 52, No. 1, January-March, 2004, pp. 127

Letter To Editor

Neurocutaneous melanosis: Criteria for diagnosis

Sanyal SK, Gupta A

Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi
Correspondence Address:Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi adtyagupta71@hotmail.com

Code Number: ni04039

Sir,

We read with great interest the case report by Ahuja et al[1] of a child, 6 weeks old, with multiple giant congenital melanocytic nevi and central nervous system melanosis. Neurocutaneous melanosis has been reported to manifest itself most commonly within the first two years of life[2] and children with this entity have been born as still births or have been reported at as early as one month of age.[3] However we agree that such a young age has not been probably reported before in Indian literature. We are very impressed at the fact that the authors suspected the entity of neurocutaneous melanosis in view of the fact that the child had multiple giant nevi located on the scalp, neck and posterior axilla (which are said to be risk factors for CNS melanosis)[2] and proceeded to a MRI of the brain even though the baby was neurologically normal.

However, if one goes through the two landmark articles on this entity by Kadonaga et al[2] and Fox et al[3] one would come to the conclusion that this case reported would only qualify as a ′provisional′ case of neurocutaneous melanosis. Both Fox and Kadonaga have laid down criteria for the diagnosis of neurocutaneous melanosis which are as follows :

1. Unduly large or unusually numerous pigmented cutaneous nevi in association with CNS melanosis or melanoma. This patient qualified this criteria.
2. No incidence of malignant change in any of the cutaneous lesions, except in patients in whom the examined areas of the CNS lesions are histologically benign. This criteria is very important because a significant percentage of patients with large congenital melanocytic nevi develop cutaneous melanoma[4] and when cutaneous melanoma is present, the estimated incidence of CNS metastases is about 40%.[3] Therefore if the CNS lesions have not been proved to be benign the cutaneous lesions have to be proved benign to rule out the possibility of the CNS lesions arising just out of metastases from a cutaneous melanoma.

Such histological confirmation would require at least a skin biopsy and/or autopsy on the death of the patient. Without this histological confirmation this case can best be labelled ′provisional′ on the assumption that the skin lesions are benign and the CNS lesions are not metastases from a cutaneous melanoma. This concept of a provisional diagnosis of neurocutaneous melanosis has been advocated by Kadonaga.[2]

The other strange about this case is the location of the CNS lesions in the amygdala and the thalamus. Fox[3] and Kadonaga[2] both have reported the leptomeninges to be the most commonly involved site of CNS melanosis. However, both these sites have been reported though rarely to be involved in CNS melanosis.

References

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