Adenoid Cystic Carcinoma

 Only a few cases have metastasized, usually to lymph nodes and lungs






Macroscopic




• Usually a few centimeters, can be up to 8 cm


Microscopic




• Composed of infiltrative lobules, islands, and cords of basaloid cells
image Numerous cystic and ductular spaces with prominent cribriform pattern

• Cells are typically small, relatively monomorphic appearing, and cuboidal shaped


Ancillary Tests




• Epithelial cells stain positive with EMA, CEA-m, and cytokeratins (low and high molecular weight keratins)

• S100, p63, GFAP, SMA, MSA, and calponin often stain peripheral cells, consistent with myoepithelial differentiation


Top Differential Diagnoses




• Basal cell carcinoma (BCC)

• Metastatic adenoid cystic carcinoma

• Other primary cutaneous adnexal tumors

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Adenoid Cystic Carcinoma
Adenoid cystic carcinoma (ACC) at low magnification shows a dermal-based basaloid neoplasm with numerous cribriform spaces image containing basophilic mucin and showing a prominent Swiss cheese-like pattern.


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Adenoid Cystic Carcinoma With Prominent Mucin
Higher magnification of ACC shows relatively bland basaloid cells surrounding the ductal lumina containing prominent collections of blue mucinous material.

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Adenoid Cystic Carcinoma With Perineural Invasion
ACC frequently shows perineural invasion, which accounts for its high local recurrence rate. Here, a large central nerve image is surrounded by multiple tumor cords and ducts.

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SMA Immunohistochemistry in ACC
ACC typically demonstrates expression of myoepithelial markers including SMA (shown here), MSA, calponin, cytokeratins, S100, and GFAP.


TERMINOLOGY


Abbreviations




• Adenoid cystic carcinoma (ACC)


Synonyms




• Primary cutaneous adenoid cystic carcinoma


Definitions




• Rare adnexal tumor showing prominent cribriform pattern and perineural invasion


ETIOLOGY/PATHOGENESIS


Unknown




• May be related to chronic sun damage in some cases

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Adenoid Cystic Carcinoma
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