|LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 2 | Page : 123-125
Melanoacanthoma: a mirage of melanoma
Raveendran Premjith, Kaliaperumal Karthikeyan MBBS MD , Manoharan Prarthana
Department of Dermatology, Venereology and Leprosy, Sri Manakula Vinayagar Medical College and Hospital, Puducherry, India
|Date of Submission||21-Sep-2020|
|Date of Decision||01-Mar-2021|
|Date of Acceptance||15-Apr-2021|
|Date of Web Publication||22-Jul-2021|
Dr. Kaliaperumal Karthikeyan
Professor and HOD, Department of Dermatology, Venereology and Leprosy, Sri Manakula Vinayagar Medical College and Hospital, Puducherry - 605 107
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Premjith R, Karthikeyan K, Prarthana M. Melanoacanthoma: a mirage of melanoma. Pigment Int 2021;8:123-5
Melanoacanthoma was originally described by Bloch in 1927 as “non-nevoid melanoepithelioma type 1.” This neoplasm represents a slow growing, usually solitary growth seen over the head and neck, or trunk of middle aged or geriatric population. It differs from the usual type of pigmented seborrheic keratosis by marked increase in the concentration of melanocytes that are scattered throughout the tumor lobules instead of confining to the basal layer. It is seen more commonly in light skinned individuals and manifests as pigmented papules, plaques, cutaneous horns, or nodules.
We present a case of melanoacanthoma in an aged female over the periareolar region of right breast that was a cause of anxiety and apprehension in the patient.
A 72-year-old female presented with the history of painless dark colored verrucous growth over right breast for the past 10 years. The lesion started as an asymptomatic small growth over the right periareolar region of breast and then progressively increased to attain the present size. There were no concomitant comorbidities or use of medications. Cutaneous examination showed a solitary well circumscribed hyperpigmented verrucous plaque measuring 3 × 3 cm over the periareolar region of right breast [Figure 1]. It was nontender, soft, and was not associated with regional lymphadenopathy. A differential diagnosis of giant seborrheic keratosis, melanoacanthoma, melanoma, and nevoid hyperkeratosis was considered. She was investigated and her routine lab investigations were within normal limits.
|Figure 1 A single well circumscribed hyperpigmented hyperkeratotic plaque measuring 3 × 3 cm over the periareolar region of right breast|
Click here to view
Shave biopsy of the lesion was done and histopathological examination of biopsied specimen revealed epidermis with marked acanthosis, papillomatosis, and focal parakeratosis. Numerous horn cysts were seen. The acanthotic epithelium was predominantly composed of melanocytes and keratinocytes with melanin pigment. Dermis showed mild lymphocytic infiltrate with melanin incontinence. There were no features suggestive of atypia or invasion [Figure 2]. All these findings were diagnostic of melanoacanthoma.
|Figure 2 Hyperkeratotic and acanthotic epidermis that is composed of melanocytes and keratinocytes with numerous horn cysts (H and E, ×10). H and E, hematoxylin and eosin|
Click here to view
Mishima and Pinkus coined the term melanoacanthoma to describe the type 1 lesion and identified the type 2 lesion as a pigmented seborrheic keratosis. Melanoacanthomas manifest as pigmented papules, plaques, cutaneous horns, or nodules and are more frequently seen in middle-aged and the elderly like any other type of seborrheic keratosis. Most commonly seen on the trunk or head, often on the lips or eyelids. It has not been described on the breast. Most of the patients are asymptomatic and may wait for years before they seek treatment. The differential diagnosis of condition is given in [Table 1]. Two histologic types of melanoacanthomas are described: a 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.,
A few studies suggest that it could be a localized phenomenon induced by trauma. The presence of a large number of melanocytes even deep into the tumor mass instead of restricting itself to the basal layer differentiates it from pigmented variant of seborrheic keratosis. Electron microscopy confirms the presence of dendritic melanocytes and is due to a failure of melanin transfer from melanocytes to keratinocytes. Because of the appearance and pigmentation, melanoacanthoma bears a striking resemblance to melanoma [Table 2], which causes apprehension in both the patient and the primary care physician. Local surgical excision is generally curative. Cryotherapy, laser ablation, and curettage are also effective. In our case, the patient was very anxious since the lesion was over the breast. The patient was counselled and explained about the benign nature of disease. This case is presented for its rarity and site of presentation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Shankar V, Nandi J, Ghosh K, Ghosh S. Giant melanoacanthoma mimicking malignant melanoma. Indian J Dermatol 2011;56:79-81.
] [Full text]
Vasani RJ, Khatu SS. Melanoacanthoma: uncommon presentation of an uncommon condition. Indian Dermatol Online J 2013;4:119-21.
] [Full text]
Mishima Y, Pinkus H. Benign mixed tumor of melanocytes and malpighian cells. Melanoacanthoma: its relationship to Bloch’s benign non‑nevoid melanoepithelioma. Arch Dermatol 1960;81:539‑50.
Shenoy MM, Teerthanath S, Bhagavan KR. Genital and perianal melanoacanthomas. Int J Dermatol 2007;52:109-10.
Barnhill RL. Pathology of Melanocytic Nevi and Melanoma. 3rd ed. New York, NY: Springer; 2014.
[Figure 1], [Figure 2]
[Table 1], [Table 2]