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.

An introduction to dermatopathology is in the dermatopathology article.

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]

Etiology:

  • Autoimmune disease, T-cell–mediated.[4]

Microscopy

Features:[5]

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

Images:

Lichen sclerosus

  • AKA chronic atrophic vulvitis (when vulvar lesion).

Etiology

  • Scratching due to pruritis.

Histology

Key feature:[6]

  • Subepithelial fibrosis.

Lichen simplex chronicus

General

  • Variant of spongiotic dermatitis.[7]

Etiology:[8]

  • Pruritus -> mechanical trauma -> lichenification (thickened/leathery[9].

Microscopic

Features:[6]

  • Acanthosis (epithelial thickening).
  • Hyperkeratosis.

Other features:[10]

  • 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.:[11]

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.[12]
  • 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:[13]

  • 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.[14]

Pilomatrixoma

General

  • Benign skin tumour.
  • Most common solid skin tumour of children.[15]

Clinical:

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

Treatment:

  • Surgical excision.[15]

Microscopic

Features:[16]

  • 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:[17]
    • 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:[18]

  • 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.[19]

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.[20]

Clinical

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

Microscopic

Features:[21]

  • 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:[22]

  • 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.[23]

Dermal perivascular lymphoeosinophilic infiltration (DPLI)

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

DDx:[23]

  • Insect bite - classically wedge-shaped.[24]
  • Drug reactions.
  • Urticarial reactions.
  • Prevesicular early stage of bullous pemphigoid.
  • HIV related dermatoses.

Notes:

  • May superficially resemble cutaneous lymphoma.[24]

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. ↑ URL: http://emedicine.medscape.com/article/1078327-overview. Accessed on: 11 September 2010.
  5. ↑ URL: http://emedicine.medscape.com/article/1078327-overview. Accessed on: 11 September 2010.
  6. ↑ 6.0 6.1 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.
  7. ↑ Tadrous, Paul.J. Diagnostic Criteria Handbook in Histopathology: A Surgical Pathology Vade Mecum (1st ed.). Wiley. pp. 296. ISBN 978-0470519035.
  8. ↑ URL: http://emedicine.medscape.com/article/1123423-overview. Accessed on: 20 August 2010.
  9. ↑ URL: http://www.medterms.com/script/main/art.asp?articlekey=10131. Accessed on: 20 August 2010.
  10. ↑ URL: http://emedicine.medscape.com/article/1123423-diagnosis. Accessed on: 20 August 2010.
  11. ↑ URL: http://missinglink.ucsf.edu/lm/DermatologyGlossary/verruca_vulgaris.html. Accessed on: 14 July 2010.
  12. ↑ http://www.missionforvisionusa.org/anatomy/2006/08/what-is-molluscum-contagiosum.html
  13. ↑ need ref
  14. ↑ http://emedicine.medscape.com/article/1059477-overview
  15. ↑ 15.0 15.1 http://emedicine.medscape.com/article/1058965-overview
  16. ↑ http://emedicine.medscape.com/article/1058965-diagnosis
  17. ↑ http://www.bccancer.bc.ca/HPI/CE/cytotechnology/cytosleuthquiz/nongyne/ngcase02d.htm
  18. ↑ URL: http://emedicine.medscape.com/article/1059871-diagnosis. Accessed on: 12 May 2010.
  19. ↑ URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC475744/. Accessed on: 11 May 2010.
  20. ↑ 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.
  21. ↑ Klatt, Edward C. (2006). Robbins and Cotran Atlas of Pathology (1st ed.). Saunders. pp. 378. ISBN 978-1416002741.
  22. ↑ 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.
  23. ↑ 23.0 23.1 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.
  24. ↑ 24.0 24.1 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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