Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
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        Keratodermas, Cornification Disorders, Nail problems, etc.

These disorders could be grouped as "rough skin", "sand paper skin", "fish scale skin", "spiky skin", "rough bumps skin", or "scaly skin". Purely speaking, skin "dysplasias" are instances of faulty skin development, whether primary (inherited...genetic, "genodermatoses" [genetically inherited skin syndromes of all types]) or secondary. They may involve ectodermal (skin surface) or dermal (skin subsurface or "hide") components...or both...and may be associated with defects in other organ systems. Keratodermas (hyperkeratosis...tylosis) are ectodermal dysplastic dermatoses (skin disorders) with a pattern of hyperkeratosis...if fish-scale-like (fine or coarse), "ichthyosiform" dermatoses or types of ichthyosis (there is loss of granular layer in ichtyosis vulgaris [S10-8783]).

The group of disorders known as palmar plantar keratodermas (PPK) is characterized by diffuse or localized hyperkeratosis of the palms and soles with additional skin abnormalities. Clinically three patterns have been identified: diffuse over the palm and sole, focal with large keratin masses at points of friction (S-03-3771...colloid keratosis, below), and punctate with tiny drops of keratin on the palmoplantar surface.

In addition, PPK-like cases associated with oral, hair, nail, dental, auditory, or neuronal abnormalities have been termed palmoplantar ectodermal dysplasia (PED). 

And there are other inherited genodermatoses (inherited keratodermas) such as the ichthyosis syndromes.

In addition to the inherited disorders,  acquired or secondary disorders may have an associated keratoderma.  See more complete write up at PS's site.

I promise the reader of this page that there are probably errors in placement of acquired and genetic entities. The idea is to get you into the possibilities.

Because the clinical info given on the biopsy requisition sheet may be incomplete, it is advisable to remember that verrucous carcinoma can present as an isolated, odd plantar [S-03-10527] or palmar keratosis.

Nail conditions, nomenclature:

(Use this page to get a category & search engine for more specific info.)

onychodystrophy (mal-development of nails):

  • leukonychia: a white discoloration of the nail secondary to color change in the nail bed. Terry's nails exhibit almost complete white discoloration except for the distal edge; they occur most commonly with cirrhosis and congestive heart failure. The discoloration of half-and-half nails affects the proximal half of the nail; they occur with chronic renal failure. Muehrcke's lines are narrow, white transverse lines (usually two); they occur with hypoalbuminemia. Mee's lines resemble Muehrcke's lines, but the lines are thicker and may be single or multiple. Mee's lines occur with arsenic exposure.
  • onychatrophy (underdevelopment of nails).
  • onychogryphosis: nail hypertrophy (see pachyonychia, below)...becomes like a claw; most of them are caused by trauma and aggravated by foot wear; a minority are developmental (especially when other toe nails are affected) or idiopathic; when most of them are thick, neglect in cutting or vascular insufficiency are likely of the so-called "trophic changes of the leg" (atrophic...sparseness of hair, thin skin, poor-growing, often thick toenails) in vascular insufficiency.
  • onychauxis/onychophyma (anatomically ordinary, unusually large nails)
  • onychoheterotopia (condition of displaced nails)
  • onychocryptosis: ingrown toenail
  • onycholysis (separation or loosening of nail from nail bed)
    • distal onycholysis (separating at the free end)
    • onychomadesis/onychoptosis (separating at the lunula toward free edge)
  • onychomalacia (softening of nails)
  • brittle/breaking nails:
    • onychorrhexis (all sorts of breakage/cleavage of nail)
    • onychoschizia (free edge separation into lamellae)
  • pachyonychia (thick nails...onychauxis):
    • onychogryphosis (curved, claw-like nails): see above.
    • onychomycosis (nail fungus thickening)
    • pseudomycotic onychoses:
      1. erythrasma of the nails (Corynebacterium-infested, colloid keratosis thickening of nail...AFB+; Wood's light +) Med. Cut. Ibero Lat. Am. 4(5):349-357, 1976.
      2. acquired eczematous palmoplantar ectodermal dysplasia [S-02-11582...colloid keratosis].
      3. acquired thickening due to eczematous etiologies [S-04-6149; L08-12970...colloid keratosis].
      4. perionychial hyperkeratosis related to an ingrown nail can have colloid keratosis [L08-13099].
    • onychoclavus: not a true pachyonychia, this has also been referred to as either a subungual heloma or a subungual corn. This represents a hyperkeratotic process in the nail area that is caused by either anatomic abnormalities or mechanical changes in foot function. The heloma is most commonly located under the distal nail margin and results from repeated minor trauma with accompanying localized pressure on the distal nail bed and hyponychium.
  • other:
    • onychopathology: study of nail diseases.
    • landmarks:
      • nail fold: skin surrounding the nail which tends to form a nail groove arround the nail.
        • eponychium: is the proximal nail fold component with the keratotic true cuticle distal to and surmounting the eponychium which is the distal crown of the proximal nail fold.
        • perionychium: the fold of skin to the sides of the nail plate...a fold infection or inflammation is a paronychium.
        • hyponychium: the skin junction distal to the nail bed, underneath the free edge of the nail.
      • nail plate: the actual hard nail.
      • nail bed: the "quick" underneath the nail plate.
      • nail root: the nail & nail bed extension proximally under the eponychium.
    • onychosis: any disease/abnormality of nails.
    • pitting: small pits in the nail surface where tiny parakeratotic mounds fell out.
    • colloid keratosis: keratotic thickening containing dense (often d-PAS+) serum inclusions (a nonspecific finding...reflecting chronic spongiotic, eczematous dermatitis or more local, intense, spongiosis) & may include onychomycosis [S-06-7477]).
    • erythronychia: longitudinal erythronychia indicates onychopapilloma (90%) or Bowen's disease. Shared clinical features in addition to erythronychia (or sometimes an interrupted line made up of splinter hemorrhages) were typically a longitudinal marked ridge of the nail bed expanded at the distal nail bed as subungual keratosis, and associated localized onycholysis.  In all cases of onychopapilloma of the nail bed, acanthosis and papillomatosis were evident, and were associated with a keratogenous zone identical to the nail matrix ( 'onychopapilloma' [nail-producing papilloma]).
  • Alopecia (hair loss): HERE (this website) & HERE & HERE15.
  • Hypertrichosis or hursuitism (excess hair): HERE14 & HERE15.
  • Altered hair cycle:
    • prolonged cycle or increased retention in follicles:
      • trichostasis spinulosa10: looks like small blackheads but is mix of sebum sticking numerous vellus hairs together.
    • reduced cycle or reduced retention in follicles:
  • Altered hair shapes (hair shaft defects): HERE14.
  • Altered growth rates:
    • increased rate:
      • hyperthyroidism
    • decreased rate:
      • hypothyroidism
  • Altered texture:
    • becomes brittle:
      • hypothyroidism
      • toxic alopecia
  • Altered color: HERE14.


  1. Fitzpatrick [dermatology text] 4th Ed, 2 vols [in LMC library]
  2. see University of Iowa Dept. of Dermatology website classification page
  3. check individual diseases, above, through links in "Disease Database"
  4. much of above after Doctor's Doctor, Dr. Paul Shitabata's website.
  5. an outstanding clinical diagnostician dermatologist is Kenny Grier in Charlottesville, Va.
  6. Hersle K & Mobacken H, Hyperkeratotic Dermatitis of the Palms, British J. Derm. 107:195-202, 1982.
  7. Excellent nail pathology photo collection on New Zealand Dermatological Society on GPs & then on GP lectures.
  8. genetic subcategories list for genodermatoses at Telethon Institute of Genetics and Medicine in Napoli,
  9. Murphy GF,Dermatopathology[textbook], 1995 (in EBS's office)
  10. dermatology area of e-Medicine website.
  11. website.
  12. Ackerman AB, A Philosophy of Practice of Surgical Pathology: Dermatopathology as a Model, Ardor Scribendi, Ltd., 1999, 470 pages.
  13. Nail Disease: Signs for the Internist, Cleveland Clinic website (
  14. PhD imunodermatologist, Kevin ?'s website.
  15. Wrong Diagnosis website.

(posted 23 September 2002; latest addition 19 September 2010)

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