Detachment of desmosomes in a microcystic meningioma.

This report demonstrates the detachment of desmosomes in the microcystic area of a frontal convexity meningioma removed from a 69-year-old woman. Well-developed interdigitations of the tumor cell processes with numerous desmosomes and with narrow extracellular spaces were characteristic features of the solid area of the meningioma. By contrast, the microcystic area of the tumor had markedly distended extracellular spaces. Various stages in the separation of desmosomal attachments were seen in this area. The observed configurations ranged from the widening of opposing junctions to the formation of large cavities where hemidesmosome-like structures were evident. The latter lacked basal lamina, and are considered to represent a transition leading to the loss of desmosome, and thus involved in the enlargement of the extracellular space in microcystic meningiomas.