Consumption of the Epidermis: A Criterion in the Differential Diagnosis of Melanoma and Dysplastic Nevi That is Associated With Increasing Breslow Depth and Ulceration

Prognostic Significance of Incipient Ulceration in Primary Cutaneous Melanoma

Importance

Ulceration represents a key feature in cutaneous melanoma, contributing to staging according to the current American Joint Committee on Cancer (AJCC) system. However, cases with incipient ulceration do not quite fulfill the AJCC definition of ulceration and are consequently classified as nonulcerated, presenting interpretive difficulty for pathologists. The prognostic implication of incipient ulceration is uncertain.

Objective

To evaluate the prognostic significance of incipient ulceration in cutaneous melanoma.

Design, Setting, and Participants

This case-control study consisted of resected primary cutaneous melanomas diagnosed between 2005 and 2015, identified from the Melanoma Institute Australia research database and with slides available for review at Royal Prince Alfred Hospital. Slides were reviewed by pathologists experienced in the diagnosis of melanocytic lesions to identify cases (incipient ulceration) and controls (ulcerated or nonulcerated). Incipient ulceration cases were matched at a 1:2 ratio with nonulcerated and ulcerated controls, respectively. Study analysis was conducted from March to June 2023.

Main Outcomes

Clinicopathological factors and clinical outcomes: overall survival (OS), melanoma-specific survival (MSS), and recurrence-free survival (RFS) were compared between cases and controls.

Results

Of 2284 patients with melanoma identified, 340 patients (median [IQR] age, 69 [24-94] years; 136 [68%] men; median follow-up, 7.2 years) met the criteria. The matched cohort consisted of 40 cases of incipiently ulcerated melanoma matched 1:2 with 80 nonulcerated controls, and 80 ulcerated controls. The median (IQR) Breslow thickness differed significantly between cases and controls; 2.8 (1.7-4.1) mm for incipient cases compared with 1.0 (0.6-2.1) mm and 5.3 (3.5-8.0) mm for nonulcerated and ulcerated melanomas, respectively. Median (IQR) tumor mitotic rate was 5.0 (3.0-9.0) per mm2 in incipiently ulcerated cases compared with 1 (0-3.0) per mm2 in nonulcerated controls and 9 (5.0-14.0) per mm2 in ulcerated controls. Based on the matched cohorts, patients with nonulcerated tumors had significantly better OS (hazard ratio [HR], 0.49; 95% CI, 0.27-0.88; P = .02) and RFS (HR, 0.37; 95% CI, 0.22-0.64; P < .001) than patients with incipient ulceration. The RFS was significantly worse in ulcerated tumors compared with incipiently ulcerated cases (HR, 1.67; 95% CI, 1.07-2.60; P = .03). After adjusting for pathological factors, no statistically significant differences in clinical outcomes were observed between cases and either control group.

Conclusions and Relevance

The findings of this case-control study indicate that incipient ulceration in a primary melanoma represents an adverse prognostic feature that should be noted by pathologists in their reports and considered in future guidelines.

Pushing and loss of elastic fibers are highly specific for melanoma and rare in melanocytic nevi

The histopathological differentiation of melanocytic nevi from malignant melanoma (MM) is based on well-known criteria, and is straightforward in the vast majority of cases. However, there are few cases of melanocytic lesions (ML), the diagnosis of which is very challenging or even impossible. Here we have studied several morphological characteristics with particular focus on elastic fibers (EF) to identify features, helpful for the distinction between nevi and MM. In a monocentric retrospective study we have analyzed 14 morphological histological characteristics in 30 MMs and 90 nevi, encompassing 30 compound/dermal nevi, 30 junctional nevi, 30 dysplastic nevi. All consecutive cases were retrieved from the archives of our tertiary referral centre during the 6-month study period. Nine characteristics including loss of EF in the ML, loss of EF in lesional fibrosis, pushing of the EF, UV-elastosis, loss of rete ridges of the epidermis, regression of the ML, atrophy of the epidermis, pigment incontinence, and concentric eosinophilic fibroplasia (CEF) showed a statistical significant difference (p < 0.05 and at least an OR > 2) distinguishing nevi from MM. Loss of EF was found in 73.1% of MM cases, but in less than 2.5% of nevi. We identified nine morphological characteristics that are helpful to differentiate melanocytic nevi from MM. A loss of the EF in a ML appeared to be highly associated with MM.

Melanocytic Matricoma With Consumption of the Epidermis: An Atypical Histologic Attribute or a Malignant Variant?

Melanocytic matricoma is a recently described cutaneous adnexal tumor composed of matrical and supramatrical cells admixed with pigmented dendritic melanocytes, thought to recapitulate the anagen bulb of the hair follicle. We report a case of a 75-year-old white man, which demonstrates consumption of the epidermis that is defined as thinning of the epidermis with attenuation of the basal and suprabasal layers and loss of the normal rete architecture in areas of direct contact with neoplastic cells. It has been associated with aggressive histologic features in melanoma and likely represents an early phase of ulceration due to attenuation. Epidermal consumption has not been previously reported in nonmelanocytic tumors and it is uncertain whether this atypical histologic feature represents a sign of malignant behavior in this rare tumor.

Consumption of the epidermis: a suggested precursor of ulceration associated with increased proliferation of melanoma cells

It has recently been demonstrated that the extent of ulceration and the presence of epidermal involvement that theoretically precede ulceration (consumption of epidermis, COE) or seen subsequent to inflammation (reactive epidermal hyperplasia or re-epithelialization) allowed better prognostic stratification of ulcerated melanoma. Understanding why these histopathologic markers have prognostic potential is important, not least because accurate consensual assessment of ulceration lies at the root of proper staging and clinical management. The authors therefore performed immunohistochemical analyses of tumor cell proliferation (Melan-A/Ki67) and infiltration of inflammatory cells (CD66b neutrophils and CD163 macrophages) to better understand the biology of the epidermal changes described. Tumors with a COE configuration showed 37% (95% CI: 4-54, P = 0.0046) increased tumor cell proliferation compared with tumors of normal epidermal configuration. COE is therefore suggested a precursor of ulceration associated with increased proliferation of melanoma cells. There was no observed correlation between COE and an increased inflammatory response (CD163 macrophages or CD66b neutrophils), which supports that the proliferation drive is noninflammatory. In contrast, the presence of re-epithelialization and/or reactive epidermal hyperplasia demonstrated an 18% (95% CI: 6-53, P = 0.0021) increased density of neutrophils compared with tumor with no evidence of these possibly prolonged late-stage or resolved ulcerations. These results further support the relevance of including these epidermal changes into the definition of ulceration and to define ulceration of a primary melanoma as loss of epidermis with evidence of a host response (infiltration of neutrophils or fibrin deposition) and thinning, effacement, or reactive hyperplasia of the surrounding epidermis.

Epidermal consumption in benign and malignant melanocytic neoplasms

Consumption of the epidermis associated with effacement of the rete ridge pattern has been cited as a useful criterion in the diagnosis of melanoma, but the significance of consumption in the absence of rete ridge effacement is unknown. We evaluated 701 melanocytic neoplasms for presence and 'grade' of consumption by melanocytic nests relative to diagnosis, body location, gender and age. We defined 1+ consumption as collections of melanocytes occupying greater than two thirds of the viable epidermis, with or without loss of the rete ridge pattern. Nests extending to the bottom of, within, and through the granular layer were graded 2+, 3+ and 4+, respectively. Consumption was more frequent and higher grades were found in melanomas followed by Spitz nevi compared with conventional melanocytic nevi (p < 0.001). Melanomas with higher Breslow thickness showed higher grades (p < 0.05). In conventional nevi, consumption occurred most frequently in back (13.7%), acral (11.9%) and scalp (9.8%) locations. Consumption without the requirement for rete ridge effacement occurs more frequently and at higher grades in melanoma. Higher grades correlate with higher Breslow thickness. Consumption is also common in Spitz nevi and occurs at lower grades in conventional (non-Spitz) nevi, especially on the back, the scalp and at acral sites.

Prognostic stratification of ulcerated melanoma: not only the extent matters

OBJECTIVES

For patients with melanoma, ulceration is an important prognostic marker and interestingly also a predictive marker for the response of adjuvant interferon. A consensual definition and accurate assessment of ulceration are therefore crucial for proper staging and clinical management. We evaluated the prognostic impact of the extent and type of ulceration and the epidermal involvement theoretically preceding it (consumption of epidermis and cleft formation) or seen subsequent to the inflammation (reepithelialization and reactive epidermal hyperplasia), aiming for better prognostic stratification of ulcerated lesions.

METHODS

From H&E-stained sections, the status (presence vs absence), extent (percentage of the total tumor length), and type (infiltrative vs attenuative) of ulceration and epidermal involvement were evaluated from 385 patients with cutaneous melanoma.

RESULTS

The presence of ulceration (hazard ratio [HR], 1.83), an attenuative type of ulceration (HR, 3.02), and excessive ulceration (HR, 3.57) were independent predictors of poor melanoma-specific survival. Further subdivision of minimal/moderate ulceration showed independent prognostic value only for lesions with epidermal involvement of the surrounding epidermis (HR, 1.78).

CONCLUSION

The extent and type of ulceration and involvement of the surrounding epidermis provided more accurate prognostic information than the mere absence or presence and may be useful markers allowing better stratification of ulcerated lesions.