PODIATRY SKIN BIOPSIES (SJB)

The microscopic ddx for these lesions typically includes some sort of wart (either classic myremecia or wart nos), plantar porokeratosis, callus and clavus (corn).

  • CLAVUS:  there is a cup shaped epidermal invagination with hyperkeratosis, parakeratosis and there is a reduced granular cell layer at the base of the lesion.
  • CALLUS: there is a cup filled epidermal invagination with reportedly less parakeratosis than with clavus, and there is usually a retained or even thickened granular cell layer at the base of the lesion.
  • PLANTAR POROKERATOSIS:  characterized by either a flat epidermal surface to only a mild epidermal invagination with overlying column of parakeratosis and focal dyskeratotic cells (forming  the so called coronoid lamellae).
  • WARTS:  exophytic/ papillomatous or endophytic /crateriform, with overlying hyper-parakeratosis, hypergranulosis, HPV cytopathic effect,  delicate capillaries extending up into thepapillae.  One specific subtype of wart is the myremecia (or deep plantar wart) with huge pink viral inclusions.   (it kind of resembles molluscum).  If its a wart that has the huge characteristic inclusions you can call it myremecia (deep plantar wart).  If it is a wart, but without the characteristic huge pink inclusions, call it wart, nos.
  • Additional note:  we often get very superficial biopsies that include only the superficial stratum corneum that shows hyperkeratosis and parakeratosis.  In these cases, just describe what you have (superficial skin including only stratum corneum showing hyperkeratosis and parakeratosis )and then say that its too superficial to classify any underlying lesion.

EXAMPLES:


Dx:  "Cup shaped epidermal invagination with overlying column of hyper-parakeratosis and reduced granular cell layer (see comment).

Comment:  The lesion is favored to represent a clavus (ie corn) or porokeratosis.  A resolvingwart is felt to be less likely but cannot be completely excluded.


Dx:  "Hyperkeratotic squamous lesion showing overlying column of hyper-parakeratosis (see comment).

Comment:  While the granular cell layer is present in many areas, in some areas, it may be focally reduced. There is also the focal suggestion of  papillomatosis with a few capillariesextending up intothe fibrovascular papillae.  The differential diagnosis for this lesion includescallus,  clavus (ie corn), porokeratosis and wart.


Dx:  "Cup shaped epidermal invagination with overlying column of hyper-parakeratosis and reduction in granular cell layer. (see comment).

Comment:  The lesion is favored to present either a clavus (corn) or porokeratosis.  Thepossibilities of callus and wart are felt to be unlikely.



Dx:  "Cup shaped epidermal invagination with overlying column of hyper-parakeratosis and suggestion of reduced granular cell layer (see comment).

Comment:  The lesion is favored to represent a clavus (ie corn) or porokeratosis.  The possibilities of callus and wart are felt tobe unlikely.  Remember,   these are all benign lesions and there is significant overlap between them, and mostof the time, unless it is a straightforward wart, you will need to be descriptive and just list a ddx and this is entirely acceptable to the clinician.  What you want to avoid is over calling something a wart when it isn't.