Dermoscopy Rocks

Presented by Hamish Dunwoodie, MBBS
Locum Tenens Physician,
Dakota First Nation, Portage La Prairie, Manitoba

Overview:  The patient is an otherwise healthy artist from Moncton, New Brunswick who is studying native pottery production with a First Nation's band in Manitoba.  She presented to our clinic with a one week history of a black macule on the left thenar eminence.  The patient has a past history of nonmelanoma skin cancer and is worried that this may be a melanoma.

O/E:  There is a 1 mm black macule in the above-mentioned area.  Dermoscopic image suggests a vascular lesion.  Note reddish black globules.

The lesions was shaved off, a small amount of H2O2 was applied and the residual hemorrhagic area was digested. The lesion disappeared!

Photographs:  Clinical Image, Dermatoscopic Image before shaving. Dermatoscopic image after shave and H2O2.

Discussion:  Dermoscopy established that this is a vascular lesion, a "subcorneal haematoma."  Once the dermatoscopic image was appreciated, it was gently shaved off with a # 15 scalpel and it vanished.  End of story.  We needed no special tools in this isolated practice setting to put the patient's mind at ease.  I am sure that some of our dermatoscopy experts will have more to day.

Reference:
Zalaudak I, et. al.  Dermoscopy of subcorneal hematoma. Dermatol Surg  Dermatol Surg. 2004 Sep;30( 9):1229-32.
Abstract
BACKGROUND:
Subcorneal hematoma is a pigmented skin lesion usually occurring on palms or soles after a trauma or sport activity. Clinically, it may exhibit overlapping features with acral melanoma or acral melanocytic nevi, leading to unnecessary excision of this otherwise harmless skin lesion.
OBJECTIVE:
The objective was to describe the dermoscopic features in a series of subcorneal hematomas.
METHODS:
Dermoscopic images of 15 subcorneal hematomas were evaluated for the presence of different colors and dermoscopic structures.
RESULTS:
In our series, a red-black hue was the most frequent color seen by dermoscopy (40% of the lesions) and a homogeneous pattern of pigmentation was the most frequent dermoscopic structure (53.3%). Remarkably, 40% of the lesions exhibited a parallel-ridge pattern that is usually found in early melanoma of palms and soles. In 46.7% of the lesions, red-black globules were additionally seen at the periphery as satellites disconnected from the lesion's body. Only two lesions showed either parallel-furrow or fibrillar pattern. A scratch test performed in four lesions, allowed complete or partial removal of the pigmentation.
CONCLUSION:
Dermoscopic features of subcorneal hematomas may be similar to those observed in acral melanocytic lesions. Nevertheless, in most cases the correct diagnosis can be facilitated by the presence of a red-black homogeneous pigmentation, often combined with satellite globules. A positive scratch test may be considered as an additional diagnostic clue.