Non-malignant skin disease

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Non-malignant skin disease is relatively common. The pathology may or may not be specific. Some diseases require clinical information to diagnose.

General classification (Inflammatory)

  • Bullous.
  • Interface.
  • Nodular & diffuse.
  • Spongiotic.
  • Vasculitis.
  • Perivascular.
  • Panniculitis.
  • Psoriasiform.

Tabular comparison of inflammatory skin disease (adapted from Brister[1]):

Pattern Key histologic feature Subclassifications Example
Bullous "Empty space" -Subcorneal
-Suprabasillar
-Subepidermal		 -?
-?
-?
Interface Inflammation at DE junction -Vacuolar (minimal)
-Lichenoid (band-like)		 -Erythema multiforme
-Lichen simplex chronicus (LSC)
Nodular & diffuse Nodular & diffuse ?
Spongiotic Edema between keratinocytes -Acute
-Subacute
-Chronic		 -Poison Ivy
-Nummular dermatitis
-Atopic dermatitis
Vasculitis Inflammation of vessel wall ? ?
Perivascular Inflammation around vessels ? ?
Panniculitis Inflamm. of SC tissue -Septal
-Nodular
Psoriasiform Epidermal thickening
and long rete ridges		 -Regular
-Irregular

Notes:

  • DE junction = dermal-epidermal junction.
  • The "empty space" in bullous disease in situ is filled with fluid.

Lichen planus

General

  • An oral pathology.
  • May be seen where the sun don't shine - penis,[2] vulva and vagina.[3]

Microscopy

Features:

  • Loss of rete ridges.
  • Loss of basal cells (stratum basale).
  • Interface dermatitis (lymphocytes at dermal-epidermal junction).

Ref.: http://emedicine.medscape.com/article/1078327-overview.

Images:

Lichen sclerosus

  • AKA chronic atrophic vulvitis (when vulvar lesion).

Etiology

  • Scratching due to pruritis.

Histology

Key feature:[4]

  • Subepithelial fibrosis.

Lichen simplex chronicus

General

  • Variant of spongiotic dermatitis.[5]

Etiology:[6]

  • Pruritus -> mechanical trauma -> lichenification (thickened/leathery[7].

Microscopic

Features:[4]

  • Acanthosis (epithelial thickening).
  • Hyperkeratosis.

Other features:[8]

  • Spongiosis (epidermal intercellular edema -- cells appear to have a clear halo around 'em).
  • Parakeratosis = retention of nuclei in the stratum corneum.

Images:

Seborrheic keratosis

General

  • Benign.
  • Common.

Epidemiology

  • Old people.

Gross

  • "Stuck-on" appearance - raised lesion.

Image(s):

Microscopic

Features:

  • Normal appearing epidermis - raised above skin surface.
  • "Horn cysts" - collections of keratin.

Image(s):

Verruca vulgaris

General

  • AKA Wart.
  • Etiology: HPV. (???)

Microscopic

Features:

  • Hyperkeratosis (more keratin - thick stratum corneum).
  • Hypergranulosis (thicker stratum granulosum).
  • Rete ridges lengthened (~7-10x normal).
  • Acanthosis (thickening of the stratum spinosum).
  • Large blood vessels at the dermal-epidermal junction.

Ref.:[9]

Molluscum contagiosum

  • Etiology: caused by molluscum contagiosum virus.

Microscopic

Features:

  • A suprabasilar epidermal lesion consisting of "molluscum bodies", i.e. molluscum bodies are found above the stratum basale.[10]
  • Molluscum bodies:
    • Large cells with abundant granular eosinophilic cytoplasm.
    • Small peripheral nucleus.

Image(s):

Note:

  • Molluscum bodies vaguely resemble signet ring cells -- but:
    • Cytoplasm eosinophilic and granular.
    • Nucleus usually smaller than in signet ring cell.
    • Molluscum bodies are only the epidermis - an uncommon place to find SRCs without finding them elsewhere.
  • The granular eosinophilic cytoplasm represents accumulated virons.

Dermal nevus

  • Think melanoma.

Clinical: ABCD = asymmetric, borders (irregular), colour (black), diameter (large).

Microscopic

Features:[11]

  • Symmetrical lesion.
  • "Matures" with depth - less cellular, less atypia.
  • No destruction of surrounding structures.
  • Only in dermis key feature.
    • Otherwise it is something else, e.g. dermal nevus, junctional nevus.

Microscopic

  • Basaloid cells mixed with squamous cells.
  • Keratin-filled invaginations.
  • Horn cysts - intraepidermal, brown globule-like structures.
    • Melanocytes at the dermoepidermal junction.[12]

Pilomatrixoma

General

  • Benign skin tumour.
  • Most common solid skin tumour of children.[13]

Clinical:

  • Hard nodule - calcification.
  • +/-Painful. (???)

Treatment:

  • Surgical excision.[13]

Microscopic

Features:[14]

  • Location: lower dermis/subcutaneous fat; thus, usu. surrounded by connective tissue.
  • Sharpy demarcated island of cells.
  • Calcification in 75% - with calcium staining (von Kossa).
  • Cells:[15]
    • Basaloid epithelial cells - have prominent nucleoli.
    • Anucleate squamous cells ("ghost cells").
  • Giant cell foreign body type granulomas (form in reaction to keratin).

Notes:

  • Keratin a prominent feature on cytology - lots of orange stuff.

Images:

DDx:

  • Epidermal inclusion cyst.

Syringoma

  • Benign sweat duct tumour. (???)
  • Eccrine differentiation.

Microscopic

Features:[16]

  • Proliferation of benign ducts with lined by a bilayer (as in normal sweat ducts) with abnormal architecture:
    • Tadpole like appearing ducts.

Image:

Inverted follicular keratosis

  • Benign skin lesion.
  • Rare.
  • May mimic squamous cell carcinoma or basal cell carcinoma.[17]

Images:

Dermal cylindroma

General

  • Benign skin lesion.
  • Should not be confused with cylindroma (adenoid cystic carcinoma).

Microscopic

Features:

  • Nests of cells that are surrounded by hyaline (i.e. glassy, eosinophilic, acellular) material.

Images:

Keratoacanthoma

  • Abbreviated KA.
  • Generally considered to be benign.
    • Rare reports of metastases suggesting it may be a form of squamous cell carcinoma.[18]

Clinical

  • May grow rapidly (weeks or months) then involute.
  • Main DDx is squamous cell carcinoma.
  • Exophytic lesion, well-circumscribed.

Microscopic

Features:[19]

  • Expansion of stratum spinosum - pushing tongue-like downward growth of epidermis into the dermis.
  • Keratin collection (keratin plug) at the center of lesion-superficial aspect.
  • Cells have glassy pink cytoplasm.
  • Minimal/no nuclear atypia.

Image:

Dermatofibroma

General

  • AKA fibrous histiocytoma.
  • Reactive process -- it is not a neoplasm.
  • Usually assoc. with previous trauma.
    • In women... usually legs.

Microscopic

Features:[20]

  • Prominent fibrous bundles, especially at the edge of the lesion.
    • Surrounded by spindle cells (fibroblasts).
      • Usually thought of as fibroblasts surrounded by fibrous material ("collagen-trapping").
  • Lack of adnexal structures, i.e. no sweat glands, no hair.
  • +/-Acanthosis (thickened epithelial layer - specifically thickened stratum spinosum) with basal keratinocyte hyperpigmentation.
    • May vaguely resemble basal cell carcinoma.

Images:

DDx:

  • Neurofibroma.
  • Blue nevus.
  • Dermatofibroma pertuberans (DFSP).
  • Melanoma.

Superficial dermal infiltrates

Discussed in detail by Alsaad and Ghazarian.[21]

Dermal perivascular lymphoeosinophilic infiltration (DPLI)

  • Microscopic appearance is just what it is called:
    • Lymphocytes and eosinophils around the vessels in the superficial dermis.

DDx:[21]

  • Insect bite - classically wedge-shaped.[22]
  • Drug reactions.
  • Urticarial reactions.
  • Prevesicular early stage of bullous pemphigoid.
  • HIV related dermatoses.

Notes:

  • May superficially resemble cutaneous lymphoma.[22]

Images:

Bullous disease

Main article: Bullous disease

Cysts

Main article: Dermal cysts

See also

References

  1. ↑ Brinster NK (March 2008). "Dermatopathology for the surgical pathologist: a pattern based approach to the diagnosis of inflammatory skin disorders (part I)". Adv Anat Pathol 15 (2): 76–96. doi:10.1097/PAP.0b013e3181664e8d. PMID 18418089.
  2. ↑ Teichman, JM.; Sea, J.; Thompson, IM.; Elston, DM. (Jan 2010). "Noninfectious penile lesions.". Am Fam Physician 81 (2): 167-74. PMID 20082512.
  3. ↑ Gupta, R.; Bansal, B.; Singh, S.; Yadav, I.; Gupta, K.; Kudesia, M. (2009). "Lichen planus of uterine cervix - the first report of a novel site of occurrence: a case report.". Cases J 2: 9306. doi:10.1186/1757-1626-2-9306. PMID 20062629.
  4. ↑ 4.0 4.1 Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 1065-6. ISBN 0-7216-0187-1.
  5. ↑ Tadrous, Paul.J. Diagnostic Criteria Handbook in Histopathology: A Surgical Pathology Vade Mecum (1st ed.). Wiley. pp. 296. ISBN 978-0470519035.
  6. ↑ URL: http://emedicine.medscape.com/article/1123423-overview. Accessed on: 20 August 2010.
  7. ↑ URL: http://www.medterms.com/script/main/art.asp?articlekey=10131. Accessed on: 20 August 2010.
  8. ↑ URL: http://emedicine.medscape.com/article/1123423-diagnosis. Accessed on: 20 August 2010.
  9. ↑ URL: http://missinglink.ucsf.edu/lm/DermatologyGlossary/verruca_vulgaris.html. Accessed on: 14 July 2010.
  10. ↑ http://www.missionforvisionusa.org/anatomy/2006/08/what-is-molluscum-contagiosum.html
  11. ↑ need ref
  12. ↑ http://emedicine.medscape.com/article/1059477-overview
  13. ↑ 13.0 13.1 http://emedicine.medscape.com/article/1058965-overview
  14. ↑ http://emedicine.medscape.com/article/1058965-diagnosis
  15. ↑ http://www.bccancer.bc.ca/HPI/CE/cytotechnology/cytosleuthquiz/nongyne/ngcase02d.htm
  16. ↑ URL: http://emedicine.medscape.com/article/1059871-diagnosis. Accessed on: 12 May 2010.
  17. ↑ URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC475744/. Accessed on: 11 May 2010.
  18. ↑ Mandrell JC, Santa Cruz D (August 2009). "Keratoacanthoma: hyperplasia, benign neoplasm, or a type of squamous cell carcinoma?". Semin Diagn Pathol 26 (3): 150–63. PMID 20043514.
  19. ↑ Klatt. AOP. P. 378.
  20. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 492. ISBN 978-0781765275.
  21. ↑ 21.0 21.1 Alsaad, KO.; Ghazarian, D. (Dec 2005). "My approach to superficial inflammatory dermatoses.". J Clin Pathol 58 (12): 1233-41. doi:10.1136/jcp.2005.027151. PMID 16311340.
  22. ↑ 22.0 22.1 Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 1269. ISBN 0-7216-0187-1.
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