Dermatopathology is both exciting and exasperating. tum corneum cells.
This occurs in disorders of keratiniza- Skin has an elegant simplicity
in its functions yet a tion because the process of desquamation is
disturbed (Figure 1. 1). ferocious complexity in its structure. This is
one of the paradoxes that underly the pathology of skin disease
Parakeratosis. The presence of nucleated horn cells in and may go some
way in explaining the multitudinous the stratum corneum. Normally the
horn cells (corneocy- disorders to which the skin is subject. The ready
visibility tes) are thin lamellae of less than 1 f. lm thickness. They
of the skin may also help explain why straightforward contain no
detectable cytoplasmic contents as these are histological examination
cannot always provide an lost in the granular cell layer. Parakeratosis
occurs when answer to a clinicians's question. Quite dramatic appear-
the process of keratinization is disturbed such as when ances may be due
to alterations of the relative rates of the rate of epidermal cell
production is increased (as in blood flow, with or without oedema, in
the different psoriasis) so that nuclei are not broken down before the
vascular plexuses or around different structures in the stratum corneum
is reached and when damage occurs horizontal dimension, neither of which
may result in to the upper epidermis (Figure 1. 2). 'much to see'
histologically. The inherent sampling error Porokeratosis.
