Early malignant melanoma manifested as longitudinal melanonychia: subungual melanoma may arise from suprabasal melanocytes

Nail matrix biopsy of longitudinal melanonychia: Diagnostic algorithm including the matrix shave biopsy

Longitudinal melanonychia (LM) may represent nail matrix melanocyte activation (defined as a normal number of melanocytes with increased production of melanin), benign hyperplasia, or melanoma, in addition to multiple nonmelanocyte pathologies, including hemorrhage and infection. This article details an algorithmic approach to LM, including a careful history and physical examination, dermoscopy, and ability to sample the matrix using 3 biopsy techniques, a 3-mm punch excision, a lateral longitudinal excision, and a matrix shave biopsy. Facility with all 3 techniques will allow the physician to procure appropriate nail matrix specimens for diagnosis.

Unusual melanoma types

This article describes that the diagnosis of melanoma has improved with such tools as epiluminescence microscopy. There remain, however, a number of unusual types of melanoma that are difficult to diagnose by virtue of their atypical or subtle morphology. The prognosis of these melanomas is often worse than for their more typical counterparts, often because of a delay in diagnosis. An appreciation of some of these unusual forms of melanoma which helps the clinician to diagnose these lesions earlier, thereby reducing patient morbidity and death is also discussed.

Pitfall in pigmentation: pseudopods in the nail plate

BACKGROUND

We present here a patient with an unusual type of nail plate pigmentation featuring pseudopod formation.

OBJECTIVE

To identify additional dermoscopic criteria.

METHODS

Dermoscopy of the nail with control biopsy.

RESULTS

Pseudopods of the nail resulted from erythrocytes entrapped between the layers of the nail plate.

CONCLUSION

Pseudopod formation of the nail may represent a diagnostic criterion to distinguish hemorrhage and melanoma of the nail apparatus.