Munro's microabscesses are seen in: (AIPG 2012)
1). In psoriasis the increased rate of proliferation (to replace the damaged, exfoliated keratin) is reflected in epidermal thickening (acanthosis), down growth of elongated epidermal ridges, and increased mitotic activity.
2). The stratum granulosum is thin or absent, and there is extensive overlying parakeratotic scale.
3). The dermal papillae are elongated and contain dilated capillaries; these extend close to the parakeratotic scale due to thinning of the overlying epidermis.
4). 'When the psoriatic scale is removed, this results in minute points of bleeding (Auspitz’s sign).
5). Within the epidermis are focal areas of slight edema (spongiosis); collections of neutrophils in the stratum corneum produce the characteristic Munro's microabscesses.
Various signs in psoriasis:
a. Auspitz’s sign
b. Woronoff ring
c. Garattage sign
d. Membrane of berkeley