Comparison of Clinicopathologic Features and Survival of Histopathologically Amelanotic and Pigmented Melanomas

Abstract

Importance Previous studies have reported that histopathologically amelanotic melanoma is associated with poorer survival than pigmented melanoma; however, small numbers of amelanotic melanomas, selected populations, lack of centralized pathology review, or no adjustment for stage limit interpretation or generalization of results from prior studies. Objective To compare melanoma-specific survival between patients with histopathologically amelanotic and those with pigmented melanoma in a large international population-based study. Design Survival analysis with median follow-up of 7.6 years. Setting The Genes, Environment, and Melanoma study enrolled incident cases of melanoma diagnosed in 1998-2003 from international population-based cancer registries. Participants A total of 2,995 patients with 3,486 invasive primary melanomas centrally scored for histologic pigmentation. Main Outcomes and Measurements Clinicopathologic predictors and melanoma-specific survival of histologically amelanotic and pigmented melanoma were compared using generalized estimating equations and Cox regression models, respectively. Results Eight percent of melanomas (275 of 3,467) were histopathologically amelanotic. Female sex, nodular and unclassified or other histologic subtypes, increased Breslow thickness, presence of mitoses, severe solar elastosis, and lack of a co-existing nevus were independently associated with amelanotic melanoma (each P < .05). Amelanotic melanoma was generally of a higher American Joint Committee on Cancer (AJCC) tumor stage at diagnosis (P for trend <.001) than pigmented melanoma. Hazard of death from melanoma was higher for amelanotic than pigmented melanoma [hazard ratio (HR), 2.0; 95% confidence interval (CI), 1.4-3.0; P< .001], adjusted for age, sex anatomic site, and study design variables; but survival did not differ once AJCC tumor stage was also taken into account, (HR, 0.8; 95% CI, 0.5-1.2; P = .36). Conclusions and Relevance At the population level, survival after diagnosis of amelanotic melanoma is poorer than after pigmented melanoma because of its more advanced stage at diagnosis. It is probable that amelanotic melanomas present at more advanced tumor stages because they are difficult to diagnose. The association of amelanotic melanoma with presence of mitoses independently of Breslow thickness and other clinicopathologic characteristics suggests that amelanotic melanomas might also grow faster than pigmented melanomas. New strategies for early diagnosis and investigation of the biology of amelanotic melanoma are warranted.

Clinicopathological Features and Prognosis of Sinonasal Mucosal Malignant Melanoma: A Retrospective Study of 83 Cases in a Chinese Population

“…In the present study, the overall survival of the patients with the amelanotic type was worse than that of the patients with the melanotic type. The poorer survival of the patients with the amelanotic type in the present study is in accordance with a study by Thomas et al [21] of cutaneous melanomas but not with that by Zebary et al [22] of 56 SNMMM cases. The small sample size and unique definition of the amelanotic type applied in the present study may explain the difference.…”

Undifferentiated sinonasal malignant melanoma: A case report

“…Patients with sinonasal MM often display non-specific symptoms, including nasal obstruction or epistaxis, causing clinical misdiagnosis (1). Based on melanin pigmentation, MM can be histopathologically categorized into melanotic and amelanotic subtypes (1,5). It is difficult to diagnose amelanotic MM in undifferentiated tumor cells as they exhibit negative expression of all melanocytic markers (6).…”

Lymph Node Micrometastases and In-Transit Metastases from Melanoma: In Vivo Detection with Multispectral Optoacoustic Imaging in a Mouse Model

“…Other melanoma models may also vary in their degree of FDG uptake. Primary amelanotic melanoma, which occurs in humans and accounts for approximately 10% of all melanomas (30), is much less likely to be detectable with MSOT owing to its markedly lower or even absent melanin content. Another limitation of this study that must be acknowledged is the small number of animals that were examined, which did not allow us to quantify sensitivity and specificity of the technique in the detection of melanoma metastasis with a binary classification test.…”