Indian Journal of Pathology and Microbiology
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Year : 2010  |  Volume : 53  |  Issue : 2  |  Page : 375-376
Pigmented cerebriform growth over forehead

1 Department of Dermatology, Jawaharlal Nehru Medical College, Sawangi, Wardha, Maharashtra, India
2 Department of Pathology, Jawaharlal Nehru Medical College, Sawangi, Wardha, Maharashtra, India

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Date of Web Publication12-Jun-2010

How to cite this article:
Choudhary SV, Bhake A, Singh A, Gupta S. Pigmented cerebriform growth over forehead. Indian J Pathol Microbiol 2010;53:375-6

How to cite this URL:
Choudhary SV, Bhake A, Singh A, Gupta S. Pigmented cerebriform growth over forehead. Indian J Pathol Microbiol [serial online] 2010 [cited 2022 May 16];53:375-6. Available from: https://www.ijpmonline.org/text.asp?2010/53/2/375/64290


Mishima and Pinkus [1] introduced the term melanoacanthoma, in 1960, to describe a pigmented, benign proliferation of keratinocytes and dendritic melanocytes. Melanoacanthoma is a deeply pigmented rare histological variant of seborrheic keratosis in which an acanthotic proliferation of both keratinocytes and large dendritic melanocytes is identified. We report a case of solitary melanoacanthoma.

A 42-year-old male patient, farmer by occupation, presented with slowly growing asymptomatic solid raised pigmented growth over left temple region since childhood. There was no history of bleeding from the lesion. His general physical and systemic examination was within normal limits. Cutaneous examination revealed well defined single, ovoid, firm, deeply hyperpigmented blackish, sessile growth of 5cm x 3 cm over left temple region with cerebriform surface [Figure 1]. Mucous membranes were not involved and there was no lymphadenopathy. His complete blood count and other biochemical parameters were within normal limits. Cutaneous lesion was excised completely and sent for histopathological examination which revealed hyperkeratosis, acanthosis and papillomatosis with tumor lobules composed of keratinocytes along with scattered large dendritic melanocytes with abundant melanin granules spread throughout the lesion. Pigment deposits were also prominent in the papillary dermis. Multiple small horn pearls were also seen. High power microscopy revealed cells with ovoid nuclei and cleared cytoplasm with abundance of melanin [Figure 2], [Figure 3] and [Figure 4]. In our case, complete excision of the lesion was done with radio surgery instrument.

Electron microscopic studies reveal that the transfer of melanin from these highly dendritic melanocytes to neighboring keratinocytes is either partially or, in some cases, completely disrupted. Melanoacanthoma can be found both on the skin and oral mucosa. Cutaneous melanoacanthomas manifest as slowly growing, pigmented usually solitary or multiple [2] papules, plaques or nodules involving head and neck or trunk of older people. [3],[4] It can also manifest as cutaneous horn. Histologically, two types of melanoacanthomas are described: diffuse type in which melanocytes are unevenly scattered throughout the lesion and a clonal type in which melanocytes and keratinocytes are clustered in small nests. [5] Cytologic atypia is not a feature of the melanocytes or keratinocytes in a melanoacanthoma. Other histological types of seborrheic keratoses are the most frequent acanthotic pattern, in which a thick layer of basal cells is observed interspersed with pseudo-horny cysts. Hyperkeratotic seborrheic keratoses show pronounced hyperkeratosis and papillomatosis with less acanthosis. The reticulated or adenoid type of seborrheic keratoses contains numerous thin tracts of basaloid epidermal cells that are branched and interwoven. They have less epidermal thickening, and horn pseudo cysts usually are less prominent in reticulated seborrheic keratoses. The clonal seborrheic keratoses show well-demarcated nests of basaloid or larger squamous cells within acanthotic seborrheic keratoses. In irritated seborrheic keratoses, pronounced squamous metaplasia can occur, which may be misdiagnosed as basosquamous carcinoma.

In our case, pigmented growth was seen since childhood and slowly progressive to attend the present size. We kept differential diagnosis like malignant melanoma, melanocytic nevus, epidermal nevus, nevus sebaceous and pigmented basal cell carcinoma. Histopathological examination showed absence of invasion of surrounding tissue, lack of marked atypia, mitotic activity and lack of cellular variability which rules out the possibility of melanocarcinoma. Immunoprecipitation assays and immunofluorescent studies have also shown that melanoacanthoma is unrelated to malignant melanoma. Acquired melanocytic naevus was ruled out due to lack of typical melanocyte proliferating activity at the basal cell layer of epidermis. The possibility of pigmented basal cell carcinoma was ruled out due to lack of characteristic features like basal cell monotony, peripheral palisade of cells in group, cleft like clearing around cell group and lack of loose stroma.

We report this case for its interesting findings.

   References Top

1.Mishima Y, Pinkus H. Benign mixed tumor of melanocytes and malpighian cells. Melanoacanthoma: it's relationship to bloch's benign non-nevoid melanoepithelioma. Arch Dermatol 1960;81:539-50.   Back to cited text no. 1  [PUBMED]  [FULLTEXT]  
2.Shenoy MM, Teerthanath S, Bhagavan KR. Genital and perianal melanoacanthomas. Ind J Dermat 2007;52:109-10.  Back to cited text no. 2      
3.Sexton FM, Maize JC. Melanotic macules and melanoacanthomas of the lip. Am J Dermatopathol 1987;9:438-44.  Back to cited text no. 3  [PUBMED]    
4.Delacretaz J. Melano-acanthome. Dermatologica 1975;151:236-40.  Back to cited text no. 4      
5.Prince C, Mehregan AH, Hashimoto K, Plotnick H. Large melanoacanthomas: a report of five cases. J Cutan Pathol 1984;11:309-17.  Back to cited text no. 5  [PUBMED]    

Correspondence Address:
Sanjiv V Choudhary
28, Modern Nagpur Society, Chhatrapati nagar, Nagpur
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.64290

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


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