Cath Lab Digest

Given the possible dire consequences of melanoma, prompt diagnosis is vital. Accordingly, these authors review the current literature on imaging modalities, discuss appropriate staging and biopsy pearls, and offer a compelling case study.

   Evaluation of skin lesions is among the most common queries proposed by patients who present for both general and specialized medical care. While the exact management of such lesions is currently a topic of substantial controversy, the undisputable fact remains that certain diseases of the skin, including malignant melanoma, can and will result in death if they are inappropriately treated or go undiagnosed.

   Although the presentation of malignant melanoma may occur in any area of the body, up to one-third of all presentations occur in the foot or the distal lower extremity.^1,2

   What is perhaps even more disturbing is that pedal distribution of melanoma is believed to be of a more advanced stage at the time of diagnosis due to its limited visibility, infrequent inspection and incorrect initial diagnoses.³

   In a clinical review of 38 melanoma patients, Gray and colleagues found that 32 percent of the melanomas in their series were initially diagnosed as benign lesions including bruises, granuloma, diabetic foot ulcers, warts or bacterial infections among others. They also found a significant difference in the thickness of lesions diagnosed at presentation (1.74 mm) versus late diagnosis (5.8 mm).³

   The primary approach recommended for assessment of pigmented lesions suspicious for melanoma is the ABCD qualification that Friedman described in 1985.⁴ One would evaluate a lesion for asymmetry, border, color and diameter. Full thickness dermal biopsy with histopathological examination is considered the standard of care for any lesion that raises a high index of suspicion for melanoma based on the above criteria.^5,6

Assessing The Strengths And Drawbacks Of Dermatoscopy

   Given the poor prognosis associated with delayed presentation and intervention, more aggressive surveillance is critical to improve outcomes. Aside from inquisitive visual detection, adjunctive diagnostic imaging to help facilitate diagnosis includes dermatoscopy, laser microscopy, optical tomography and high-resolution ultrasound.⁷

   Perhaps the most promising of the imaging techniques is dermatoscopy (also known as dermoscopy or epiluminescence microscopy).⁷ The primary goal of dermatoscopic examination is to differentiate between benign and malignant lesions. The technique involves the use of an oil-to-skin interface under magnification, which allows greater visualization of the epidermis and superficial dermis.^7,8 While this method is not diagnostic in and of itself, it can be useful to help increase or decrease confidence that a lesion is benign or malignant based on features one visualizes during examination.⁷

   For example, during the evaluation of non-melanotic lesions, findings such as milia-like cysts represent seborrheic keratosis and a white scar-like patch may represent dermatofibroma. In addition, a homogeneous blue color will represent a blue nevus, red-black-blue lacunae represent angioma and arborizing vessels with blue-grey globules represent basal cell carcinoma.⁷

   However, dermatoscopic examination is highly user-dependent and results are variable in inexperienced hands.^6-8 A meta-analysis of studies evaluating dermatoscopy found that this diagnostic technique was more accurate than clinical examination alone. However, the researchers noted that many of the lesions identified as negative by dermatoscopy went on to biopsy nevertheless, negating the clinical significance of the technique.⁸