Non-malignant skin disease
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
- Oral pathology.
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.
Lichen sclerosus
- AKA chronic atrophic vulvitis (when vulvar lesion).
Etiology
- Scratching due to pruritis.
Histology
Key feature:[2]
- Subepithelial fibrosis.
Lichen simplex chronicus
Histology
Key features:[3]
- Acanthosis (epithelial thickening).
- Hyperkeratosis.
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):
Molluscum contagiosum
- Etiology: caused by molluscum contagiosum virus.
Micro
- A suprabasilar epidermal lesion consisting of "molluscum bodies", i.e. molluscum bodies are found above the stratum basale.[4]
- Molluscum bodies:
- Large cells with abundant granular eosinophilic cytoplasm.
- Small peripheral nucleus.
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).
Micro
Features:[5]
- 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.[6]
Images:
- SK - wikimedia.org.
- SK - high mag. - dermatlas.org.
- SK - low mag. - dermatlas.org.
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Pilomatrixoma
General
- Benign skin tumour.
- Most common solid skin tumour of children.[7]
Clinical:
- Hard nodule - calcification.
- +/-Painful. (???)
Treatment:
- Surgical excision.[7]
Microscopic
Features:[8]
- 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:[9]
- 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:[10]
- 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 lesions.
- May mimic squamous cell carcinoma or basal cell carcinoma.[11]
Images:
Keratoacanthoma
- Abbreviated KA.
- Generally considered to be benign.
- Rare reports of metastases suggesting it may be a form of squamous cell carcinoma.[12]
Clinical
- May grow rapidly (weeks or months) then involute.
- Main DDx is squamous cell carcinoma.
- Exophytic lesion, well-circumscribed.
Microscopic
Features:[13]
- 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:
Bullous disease
Main article: Bullous disease
Cysts
Main article: Dermal cysts
See also
References
- ↑ 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.
- ↑ PBoD P.1065-6
- ↑ PBoD P.1065-6
- ↑ http://www.missionforvisionusa.org/anatomy/2006/08/what-is-molluscum-contagiosum.html
- ↑ need ref
- ↑ http://emedicine.medscape.com/article/1059477-overview
- ↑ 7.0 7.1 http://emedicine.medscape.com/article/1058965-overview
- ↑ http://emedicine.medscape.com/article/1058965-diagnosis
- ↑ http://www.bccancer.bc.ca/HPI/CE/cytotechnology/cytosleuthquiz/nongyne/ngcase02d.htm
- ↑ URL: http://emedicine.medscape.com/article/1059871-diagnosis. Accessed on: 12 May 2010.
- ↑ URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC475744/. Accessed on: 11 May 2010.
- ↑ 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.
- ↑ Klatt. AOP. P. 378.