Neurocristic hamartoma and malignant neurocristic hamartoma

    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. citation   citation citation citation

    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) citation citation 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. citation citation citation

    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.  citation

    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 citation 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:

    • Is cutaneous neurocristic hamartoma a distinct entity of just a variant of blue nevus or congenital nevus?
    • What is the natural history of this tumor?
    • What is prognostic significance of lymph node metastases in this tumor?

    Please contribute to the project by submitting your cases or expressing your opinion.


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    Sun J, Morton THJ, Gown AM. Antibody HMB-45 identifies the cells of blue nevi. An immunohistochemical study on paraffin sections. Am. J. Surg. Pathol. 1990;14;748-751.

    Pearson JP, Weiss SW, Headington JT. Cutaneous malignant melanotic neurocristic tumors arising in neurocristic hamartomas. A melanocytic tumor morphologically and biologically distinct from common melanoma. Am. J. Surg. Pathol. 1996;20;665-677 citation.

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    Betti R, Inselvini E, Palvarini M, Crosti C. Agminate and plaque-type blue nevus combined with lentigo, associated with follicular cyst and eccrine changes: a variant of speckled lentiginous nevus. Dermatology 1997;195;387-390.

    Micali G, Innocenzi D, Nasca MR. Cellular blue nevus of the scalp infiltrating the underlying bone: case report and review. Pediatr. Dermatol. 1997;14;199-203.

    10  Granter SR, McKee PH, Calonje E, Mihm MCJ, Busam K. Melanoma associated with blue nevus and melanoma mimicking cellular blue nevus: a clinicopathologic study of 10 cases on the spectrum of so-called 'malignant blue nevus'. Am. J. Surg. Pathol. 2001;25;316-323.

    11  Hendrickson MR, Ross JC. Neoplasms arising in congenital giant nevi: morphologic study of seven cases and a review of the literature. Am. J. Surg. Pathol. 1981;5;109-135.

    12  Pathy AL, Helm TN, Elston D, Bergfeld WF, Tuthill RJ. Malignant melanoma arising in a blue nevus with features of pilar neurocristic hamartoma. J. Cutan. Pathol. 1993;20;459-464.

    13.  Tuthill RJ, Clark WH, Levene A. Pilar neurocristic harmartoma: Its relationship to blue nevus and equine melanotic disease. Arch. Dermatol. 1982;118;592-596.

    14.  Bastian BC, Xiong J, Frieden IJ et al. Genetic changes in neoplasms arising in congenital melanocytic nevi: differences between nodular proliferations and melanomas. Am. J. Pathol. 2002;161;1163-1169. citation   

    15.  Smith KJ, Mezebish D, Williams J, Elgart ML, Skelton HG. The spectrum of neurocristic cutaneous hamartoma: clinicopathologic and immunohistochemical study of three cases. Ann. Diagn. Pathol. 1998;2;213-223. citation

    16.  Mezebish D, Smith K, Williams J, Menon P, Crittenden J, Skelton H. Neurocristic cutaneous hamartoma: a distinctive dermal melanocytosis with an unknown malignant potential. Mod. Pathol. 1998;11;573-578. citation

    17.  Kikuchi I, Inoue S, Taketomi I, Ono T. Two cases of nevus fuscocaeruleus with pain, including a case of pilar neurocristic hamartoma. J. Dermatol. 1983;10;275-280.




    Cases associated with this research project:

  • A consultation from Norway
    Author: Artur Zembowicz M.D. Ph.D.

    Event: Medilink Training 2nd Dermatopathology Update
    Conference: Dr. Z's Consultations