Wednesday, April 25, 2012

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.

Zalaudak I, et. al.  Dermoscopy of subcorneal hematoma. Dermatol Surg  Dermatol Surg. 2004 Sep;30( 9):1229-32.
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.
The objective was to describe the dermoscopic features in a series of subcorneal hematomas.
Dermoscopic images of 15 subcorneal hematomas were evaluated for the presence of different colors and dermoscopic structures.
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.
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.

1 comment:

  1. One pattern red or purple clods is consistent with a benign vascular lesion - blood clot or haemangioma. That diagnosis should be confidently made as long as no vessels or melanin structures are seen. Vessels may be present in a haemangioma but a biopsy needs to be considered if vessels are seen to exclude a malignant vascularised lesion (like amelanotic melanoma)


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