What Can Hide Under ExophytIc Verrucous Appearance?

Abstract

A 70-year-old Caucasian woman attended our pigmented lesions clinic for routine treatment. On examination, numerous seborrhoeic kératoses were found on her trunk and limbs. She reported that a lesion in the centre of her abdomen had increased in size over the previous year. Clinical examination revealed a symmetric lesion comprising two well distinct areas of pigmentation, one light brown and the other dark brown, and exhibiting a typical exophytic verrucous appearance (Fig. 1). Dermoscopic evaluation of the whole lesion revealed the presence of pseudo-horn cysts, comedo-like openings and fissures. Moreover, a pigmented network, as well as globules and pseudopods, were found in one part of the lesion (Fig. 2).A tentative diagnosis of collision tumour involving a seborrhoeic keratosis and atypical melanocytic lesion was made, and we decided to surgically remove the entire lesion. Histopathological examination of the excised tissue revealed a hyperkeratotic (papillomatous) seborrhoeic keratosis converging with an exophytic, verrucous lesion (displaying melanocytic activity) at the dermoepidermal junction and superficial dermis. The hyperkeratotic seborrhoeic keratosis displayed papillomatosis, acanthosis and the proliferation of basaloid cells with a varying admixture of squamoid cells, keratin-filled invaginations and hom cysts. Similar to conventional seborrhoeic keratosis, there were, at the dermoepidermal junction in the area of skin affected by seborrhoeic keratosis-like changes, nests of atypical melanocytes, some of which formed pagetoid spread in the epidermal fronds. The dermis, meanwhile, contained -20 -15 -10 -5 Fig. 2. Demiuscopic image of the same lesion shown in I ig. 1 JcniDnstrating pseudo-hom cysts, comedo-like openings and fissures. One part of the lesion also displayed a pigmented network, globules and pseudopods.tightly-packed aggregates of small darkly-staining cells resembling naevus cells. These cells displayed hypcrchromatic, angulated nuclei, scant cytoplasm and occasionally prominent nucleoli. The final diagnosis was hyperkeratotic seborrhoeic keratosis in collision with verrucous and keratotic nevoid melanoma (Fig. 3). The melanoma was a Clark level II tumour in the vertical growth phase. It had a Breslow thickness of 0.8 mm.The development of malignant melanoma contiguous with or adjacent to seborrhoeic kératoses is uncommon but has been documented previously (1-5).A retrospective analysis of 618 cases of malignant melanoma (6) identified 10 lesions with marked verrucous and keratotic patterns that were initially clinically diagnosed as benign lesions. Fig. I. Macroscopic image of a malignant melanoma arising from a seborrhoeic keratosis. Acta Derm Venereol 91 Fií^. 3. l!\pcrkcr¿iti>lic schonhocic m COIIISUMI \\ilh novoid melanoma.Melanoma cells are associated with scattered meanophages and signs of fibrosis in the superficial dermis (inset).

Dermoscopic Clues for Diagnosing Melanomas That Resemble Seborrheic Keratosis

“…In the case of tumors with verrucous presentation, it has been shown that 50% of verrucous melanomas can simulate benign tumors. 5,25,26 Verrucous melanomas are considered a specific histopathologic subtype of melanoma, for which it is mandatory to find hyperkeratosis and pseudoepitheliomatous hyperplasia of the epidermis that is intermingled with atypical melanocytes. On the other hand, the term SK-like melanoma refers to a clinical and/or dermoscopic appearance that makes the melanoma look like SK, being verrucous or not on the histopathology report.…”

“…In those cases, the clinical information, with nodular or inflamed appearance, or the given history of changes should lead physicians to rule out squamous cell carcinoma or nodular melanoma even in the absence of suspicious dermoscopic features. In the case of tumors with verrucous presentation, it has been shown that 50% of verrucous melanomas can simulate benign tumors . Verrucous melanomas are considered a specific histopathologic subtype of melanoma, for which it is mandatory to find hyperkeratosis and pseudoepitheliomatous hyperplasia of the epidermis that is intermingled with atypical melanocytes.…”

An Atlas of Dermoscopy

“…8f). Dermoscopic clues to the diagnosis of verrucous melanoma include the presence of atypical vessels and irregular pigment distribution (De Giorgi et al, 2011;Gencoglan et al, 2011). Structures such as milia-like cysts and comedo-like openings are very conspicuous and are detected almost immediately without requiring a thorough inspection of the entire lesion.…”

Seborrheic keratosis-like melanoma: a diagnostic challenge

“…Lesions with benign but unclear features should always be histologically analyzed [17]. Melanoma [18,19] or other skin cancers [20] arising in SK have been reported as well as melanoma and SK collisions [21,22]. Noninvasive optical methods, such as reflectance confocal microscopy (RCM) and optical coherence tomography, have been extensively used to improve accuracy in melanoma diagnosis although in SK-like melanoma the application has been limited due to a frequent clinical-dermoscopic misdiagnosis [23].…”