The term cutaneous neurocristic hamartoma (CNH) was applied to rare complex dermal and subcutaneous melanocytic tumors with diverse histological differentiation including melanocytic (epithelioid, spindle, dendritic), schwannian and mesenchymal/fibrotic.
CNH presents clinically as a congenital or acquired slowly enlarging multinodular variably pigmented plaque.
Head and neck and especially scalp are the site of predilection. The age of presentation varies but infrequently the lesions are brought to medical attention at young adulthood.
Histologically, CNH is a deep dermal and subcutaneous lesion without a junctional component. Involvement of fascia and subfascial soft tissues (bone, skeletal muscle) and organs (parotid gland) can occur. CNH often has a multinodular growth pattern with infiltrating border and infiltration of periadnexal connective tissue or nerves. The term pilar neurocristic hamartoma was used to describe similar lesions showing propensity to involve perifollicular adventitia in addition to forming diffuse plaques with small perifollicular nodules.
CNH is composed of a mosaic of areas reminiscent of congenital epithelioid melanocytic nevus, neurofibroma, schwannoma, and blue, cellular and epithelioid blue nevus. Bizarre architectural arrangements such as trabecular pattern, perivascular cuffing, tactile body differentiation and pseudorosette formation, rarely seen in blue or congential nevi, or common melanoma are present in some lesions. CNH may be stable but usually shows a slow progressive local growth.
Some lesions develop discrete expansile nodules composed of cytologically atypical epithelioid cells with prominent eosinophilic nucleoli, mitotic activity and tumor necrosis. These nodules can vary in degree of cytological atypia, but can show malignant features. CNH harboring malignant appearing nodules are referred to as malignant neurocristic tumors. Such tumors can metastasize and be lethal. Four of 11 reported patients died of disease 2 to 20 years (mean 9 years) after diagnosis of malignant metastasizing neurocristic tumor and many years (15 to 67) after birth with a pigmented congenital lesion.
Interestingly, comparative genomic hybridization studies of one case of CNH with 15 year clinical history of indolent local growth showed chromosomal aberrations similar to those occurring in common melanoma and melanoma occurring in congenital melanocytic nevi.
However, CHN is not an established entity and not all the current textbook of dermatopathology recognize it as a distinct disease. These lesions show some overlap with congenital nevus or so-called plaque-like blue nevus and some experts interpret these tumors as variants of congenital or blue nevus. When malignancy supervenes, the malignant tumors are classified as malignant blue nevus or melanoma supervening in congenital nevus.
The purpose of this project is to collect a large series of cases that fit description of neurocristic hamartoma and address the following questions:
Please contribute to the project by submitting your cases or expressing your opinion.
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