Title : ABCDEs of amelanotic melanoma: Delayed diagnosis case & suggested practice
Abstract:
Amelanotic melanomas are malignant neoplasms of melanocytes that occur in the skin and mucosal surfaces but lack pigmentation on examination. This case presentation provides a unique opportunity to reorient clinical criteria to improve amelanotic melanoma diagnostic speed and accuracy. Herein, we present a 58-year-old female with a family history of melanoma who presented with a “mole” that had been growing and bleeding for 1 year without improvement. Examination revealed a 1.5 cm x 1.5 cm glistening, friable, red-pink nodule overlying a well-circumscribed pink patch on the left anterior thigh. Histopathological analysis revealed confluent proliferation of atypical melanocytes confirming pT4b invasive melanoma. The patient underwent sentinel lymph node biopsy, of which two were positive for tumor. Surgical pathology confirmed nodular melanoma with spindle cell features and a maximum Breslow thickness of 11 mm. Hematology/oncology was consulted for discussion regarding adjuvant immunotherapy. Because of the lengthy time to diagnosis and extensive invasion of this illness, it is imperative to have more stringent diagnostic criteria for amelanotic melanoma. Patients with amelanotic melanoma are more likely to be clinically misdiagnosed than patients with pigmented malignant melanoma with 25% misdiagnosis rates compared to 12% for pigmented malignant melanoma. Amelanotic melanoma also has poorer survival rates in comparison to pigmented malignant melanoma with 77% compared to 84%. Thus, the classic ABCDE rule for melanoma diagnosis does not fit for amelanotic melanoma presentations. We suggest the following specific ABCDE criteria to be used instead when under diagnostic suspicion for amelanotic melanoma. A) Atypical, a lesion that is different from others; B) Bleeding, a lesion that is easily friable; C) Color, a lesion that is skin-colored, red, pink, or gray; D) Developing, a lesion that changes colors and/or grows in size or elevation; E) Exposed, a lesion in a sun-exposed area. We believe that this suggested criterion will improve diagnostic rates of amelanotic melanoma, and, ultimately, reduce mortality rates associated with this disease.
Audience Take Away Notes:
- Use of new ABCDE criteria to screen for amelanotic melanoma
- A baseline framework to improve amelanotic melanoma diagnostic criteria upon which further studies can be built
- A practical solution to improve identification of an often misdiagnosed dermatologic condition with a high mortality rate
- Improved vigilance for amelanotic melanoma when pruritic, hypopigmented lesions fail to improve
- Utilization of a new dermatologic tool to improve patient outcomes
