Background: Antibodies to CD56 label natural killer cells as well as tissues with neural and neuroendocrine differentiation. Despite its apparently limited distribution, other conditions may unexpectedly show strong CD56 expression.
Methods: We report three cases to document another setting with strong expression of CD56 in the skin: damaged and/or regenerating muscle fibers. One case of cutaneous lupus erythematosus, one case of lymphomatoid granulomatosis, and one case of a dermal scar adjacent to cutaneous muscle fibers were evaluated with a panel of antibodies, including CD56.
Results: All cases showed histopathologic evidence of muscle fiber damage in the setting of lymphocytic infiltration or trauma. All cases showed prominent expression of CD56 by damaged and/or regenerating muscle fibers. The degree of CD56 expression was directly proportional to the proximity to the injury site and inversely proportional to fiber diameter.
Conclusions: Even though CD56 is a useful marker for certain cytotoxic lymphomas and neural/neuroendocrine neoplasms, its expression is not limited to these conditions. Our cases highlight another unexpected example of strong CD56 expression in the skin: damaged and/or regenerating muscle fibers. The growing list of CD56-positive conditions suggests that this marker may not be as specific as initially assumed.
Copyright © 2011 John Wiley & Sons A/S.