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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 6  |  Issue : 2  |  Page : 93-96

Neurocristic cutaneous hamartoma: Case report of a rare entity


Department of Pathology, PES Institute of Medical Sciences and Research, Chittoor, Andhra Pradesh, India

Date of Web Publication28-Nov-2019

Correspondence Address:
Dr. B N Kumarguru
Sri'nivasa, No: 204, 9th Cross, BEML Layout, Basaveshwaranagara, Bengaluru - 560 079, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdpdd.ijdpdd_9_19

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  Abstract 


Neurocristic cutaneous hamartoma (NCH) is a rare entity characterized by hamartomatous proliferation of melanocytic, neuroid, and mesenchymal tissues. It results from the aberrant development of the neural crest cells. A 29-year-old female presented with a painless pedunculated swelling over the lower back for 1 year. Grossly, the lesion was skin covered polypoidal tissue. Cut section showed gray-white to gray-yellow areas. Histologically, the lesion was composed of mesenchymal elements and ectodermal elements. Mesenchymal elements were composed of lobules of adipocytes, bundles of smooth muscle tissue, and bone tissue. Ectodermal derivative tissues were composed of nerve bundles and melanocytes. Melanocytes showed a normal maturation pattern. Features were suggestive of a hamartomatous lesion favoring NCH. On immunohistochemistry (IHC), melanocytic cells showed strong positivity for S100. They were also positive for HMB45. Spindle-shaped cells in the connective tissue were positive for CD34. IHC supported the histopathological diagnosis. NCH is a rare entity and poses a diagnostic challenge. IHC may be helpful, but a pathologist has to primarily depend on the histopathological characteristics of the lesion for diagnosing the condition.

Keywords: Bone, connective tissue, melanocytes, neural crest


How to cite this article:
Kumarguru B N, Haripriya N, Ramaswamy A S, Nirmala M J. Neurocristic cutaneous hamartoma: Case report of a rare entity. Indian J Dermatopathol Diagn Dermatol 2019;6:93-6

How to cite this URL:
Kumarguru B N, Haripriya N, Ramaswamy A S, Nirmala M J. Neurocristic cutaneous hamartoma: Case report of a rare entity. Indian J Dermatopathol Diagn Dermatol [serial online] 2019 [cited 2020 Feb 21];6:93-6. Available from: http://www.ijdpdd.com/text.asp?2019/6/2/93/271951




  Introduction Top


Neurocristic cutaneous hamartoma (NCH) is a rare entity characterized by hamartomatous proliferation of melanocytic, neuroid, and mesenchymal tissues.[1] This entity was first described by Tuthill et al. in 1982. It was referred to as pilar neurocristic hamartoma.[2] The pathogenesis of this lesion may be attributed to the aberrant development of neural crest cells. NCH may be congenital or an acquired lesion.[3] Clinically, NCH may present as pigmented macules, papules or nodules. In general, NCH has a predilection for the scalp.[1] We, hereby, report a case of an NCH in a 29-year-old female at an unusual site.


  Case Report Top


A 29-year-old female presented with a pedunculated swelling in the lower back for 1 year. Swelling was initially small and gradually increased in size to the present size. It was not associated with pain. On examination, the swelling was located over the lumbar region, mobile and firm in consistency. There were no neurological deficits. No radiological investigations were performed. Clinically, a working diagnosis of a warty lesion was considered. The lesion was excised under local anesthesia on an outpatient procedure basis. The lesion was not involving the underlying muscle or bone tissue. The specimen was sent for histopathological examination. We received a single skin covered polypoidal tissue measuring 1.5 cm × 1 cm × 0.5 cm. The external surface was smooth and congested. Cut section showed gray-white to gray-yellow areas [Figure 1].
Figure 1: Gross photograph of skin covered the polypoidal tissue. Cut section shows gray-white to gray-yellow areas

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On microscopy, multiple sections studied showed a polypoidal lesion lined by the epidermis. The epidermis showed focal hyperkeratosis, focal parakeratosis, papillomatosis, irregular acanthosis, intraepithelial neutrophilic microabscess, follicular plugging, and focal atrophy. Also seen were yeast form of fungal elements in the stratum corneum, morphologically resembling dermatophytes [Figure 2]. Subepithelium showed sebaceous glands, focal granulation tissue response consisting of congested blood vessels, fibroblastic proliferation, and chronic inflammatory cell infiltrate. Inflammatory cell infiltrate was composed of predominantly lymphocytes, few plasma cells, mast cells, and macrophages. Also seen were mesenchymal elements composed of lobules of adipocytes, bundles of smooth muscle tissue, and bone tissue displaying mineralization front [Figure 3]. Ectodermal derivative composed of nerve bundles and melanocytes were seen. Melanocytes were seen arranged in clusters, nests, and theques [Figure 4]. Melanocytes showed epithelioid morphology in the superficial dermis lymphoid morphology in the mid-dermis and Schwannoid (spindle cell) morphology in the deeper dermis. Epithelioid melanocytic cells showed cytoplasmic pigmentation. There was no evidence of malignancy or junctional activity. Features were suggestive of a harmartomatous lesion with superficial fungal (dermatophytes) infection. A final diagnosis of hamartomatous lesion favoring NCH (with superficial fungal infection) was offered. Immunohistochemistry (IHC) was performed. The melanocytic cells showed strong positivity for S100 protein. They were also positive for HMB-45 [Figure 5]. Spindle-shaped cells in the connective tissue were positive for CD34 [Figure 6]. Ki-67 labeling did not show any significant proliferation. IHC supported the histopathological diagnosis of NCH. Postprocedure period was uneventful, and the patient was stable.
Figure 2: Microphotograph of tissue section showing epidermis displaying focal hyperkeratosis and papillomatosis. Subepithelial connective tissue shows lobule of adipocytes and bone tissue (H and E, ×40)

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Figure 3: Microphotograph of tissue section showing sebaceous glands, lobules of adipocytes, and bone tissue (H and E, ×100)

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Figure 4: Microphotograph of tissue section showing epithelioid melanocytes arranged in nests. Inset: Schwannoid melanocytes (H and E, ×400)

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Figure 5: Microphotograph of tissue section showing melanocytic cells displaying strong positivity for S100 (IHC, ×400)

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Figure 6: Microphotograph of tissue section showing melanocytic cells showing positivity for HMB-45. Inset: Spindle-shaped cells in the connective tissue being positive for CD34 (IHC, ×400)

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  Discussion Top


NCH is a rare hamartomatous skin lesion, presumably resulting from aberrant development of neuromesenchyme.[3],[4] The elements of NCH reflect the spectrum of differentiation inherent in neural crest-derived cells.[3] The lesion can harbor neurosustenticular and neuromesenchymal components.[4] They may be congenital or acquired.[1],[3],[5] NCH typically present later in childhood and more commonly in the adulthood, probably due to slower progression of the lesion.[6] Most NCH has a predilection for the scalp. However, few cases have been reported on the back, trunk, and extremities.[1.3] Clinically, they may present as pigmented macules, papules, or nodules with or without alopecia.[1] In the present case, the lesion was seen in a 29-year-old female, presenting as a pedunculated swelling in the lower back, which was an unusual location for the lesion.

The NCH consists of a combination of elements including nevomelanocytes, pigmented dendritic cells, Schwann cells, spindle cells, and fibroblasts. Thus, the pluripotent nature of neural crest cells is underscored. These lesions also contain neurosustenticular and neuromesenchymal cells. Dermal melanocytes are present in NCH but are unassociated with a junctional element.[3] In the present case, NCH was composed of ectodermal derivative tissue and mesenchymal elements. Ectodermal derivative tissue included melanocytes displaying normal maturation pattern. Previous literature documented similar histomorphological features in their case reports.[1],[2],[3] The presence of bone tissue as a part of the mesenchymal component and presence of superficial fungal infection contributed to the uniqueness of the lesion. In contrast, Conrad et al.[4] reported bone marrow involvement and Denlinger et al.[5] observed skeletal muscle involvement in their case reports. Other documented features of NCH include a prominent collection of melanocytes around hair follicles, eccrine glands, nerves and blood vessels, perivascular pseudorosettes, and tactoid bodies.[1] Occasionally, NCH may occur in the setting of other neural crest-derived disorders such as neurofibromatosis and neurocutaneous melanosis.[3]

The melanocytic cells showed strong positivity for S100 protein. They were also positive for HMB-45. Spindle-shaped cells in the connective tissue were positive for CD34. Lee et al.[1] and Kim et al.[2] also documented similar immunophenotypic characteristics. Baskara et al.[7] observed that the lesion was positive for S100, microphthalmia-associated transcription factor, melan A, tyrosinase, CD34, and HMB45.

NCH has to be differentiated from congenital nevi, blue nevi, and nerve sheath tumors (Schwannoma and neurofibroma). In NCH, the surrounding stroma and stroma with Schwannian differentiation show increased CD34-positive cells. Increased CD34 staining is seen in neurally derived tumors and marks a subset of endoneurally derived cells.[3]

Congenital nevi and blue nevi do not show stromal staining for CD34.[2],[3]

In neurofibromas and Schwannomas, the presence of abundant mast cells, marked hyperplasia of overlying epidermis, and papillomatosis is the differentiating features.[3]

Although the course of NCH is generally indolent, long-standing NCH has been reported to give rise to cutaneous malignant neurocristic tumors.[1] The time period for the development of malignant tumor has been estimated to be 1–6 years for acquired NCH and 15–67 years for congenital NCH.[1],[2] The importance of recognizing NCH is due to the possible transformation to malignant melanoma over an unpredictable period of time.[2]

Approximately 25%–33% of cutaneous melanomas arise from nevi. Junctional and compound nevi may be relatively more likely to give rise to melanoma than intradermal nevi.[8]

NCH develops into malignant melanoma because these tumors exhibit melanocytic differentiation and arise in hamartomatous lesions composed of neural crest derivatives.[9] Factors affecting the risk and onset of malignant NCH transformation are still unknown.[1]

Malignant NCH shows a less aggressive behavior than conventional malignant melanoma. Malignant tumors are usually circumscribed, multinodular lesions which tend to recur as bulky nodules and metastasize after years or decades. Patients may experience multiple recurrences and hematogeneous spread. BRAF, NRAS, GNAQ, or KIT mutations are not found in malignant NCH, suggesting that malignant NCH may be distinct from conventional melanoma.[1]

Due to a small number of cases reported, no guidelines are available for the management of NCH.[1],[3] It has been suggested that wide local excision should be considered to reduce the malignant potential.[1],[2],[3] Complete excision of the lesion is crucial as it prevents likely development of melanoma.[1],[2],[7] Early diagnosis is useful for the proper management of NCH. The optimum management should also include long-term follow-up and surveillance for the development of malignant melanoma.[2]


  Conclusion Top


NCH is a rare entity and poses a diagnostic challenge. Clinically, the lesion poses a diagnostic dilemma. IHC may be helpful, but a pathologist has to primarily depend on the histopathological characteristics of the lesion for diagnosing the condition.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

We sincerely thank the Department of Surgery, PES Institute of Medical Sciences and Research, Chittooor, Andhra Pradesh, India for the kind cooperation extended to us for the workup of the case.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Lee CC, Wu NL, Wu YH. Cutaneous neurocristic hamartoma on the scalp. Dermatol Sin 2015;33:31-2.  Back to cited text no. 1
    
2.
Kim SK, Kim YC. Neurocristic cutaneous hamartoma of the scalp. Ann Dermatol 2009;21:396-8.  Back to cited text no. 2
    
3.
Turel MK, Chacko G, Raja A, Scheithauer BW. Neurocristic cutaneous hamartoma of the scalp. J Pediatr Neurosci 2012;7:181-4.  Back to cited text no. 3
[PUBMED]  [Full text]  
4.
Conrad DM, Chaplin A, Walsh NM, Pasternak S. Extensive neurocristic hamartoma with bone marrow involvement. Am J Dermatopathol 2010;32:486-8.  Back to cited text no. 4
    
5.
Denlinger CE, Slingluff CL Jr., Mihm MC Jr., Patterson JW. Extensive neurocristic hamartoma with skeletal muscle involvement. J Cutan Pathol 2007;34:634-9.  Back to cited text no. 5
    
6.
Hadley C, Mohila CA, Luerssen TG, Lam S. Congenital neurocristic tumor presenting as an isolated calvarial defect in an infant: Case report. J Neurosurg Pediatr 2015;16:46-9.  Back to cited text no. 6
    
7.
Baskara A, Sapanara N, Medvetz L. Giant neurocristic hamartoma of scalp: A case report. Grand Rounds 2010;10:91-4.  Back to cited text no. 7
    
8.
Damsky WE, Bosenberg M. Melanocytic nevi and melanoma: Unraveling a complex relationship. Oncogene 2017;36:5771-92.  Back to cited text no. 8
    
9.
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;20:665-77.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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