Acinic cell carcinoma

Acinic cell carcinoma, abbreviated AcCC, is a rare type of salivary gland cancer. It is also known as acinic cell adenocarcinoma.

Acinic cell carcinoma
Diagnosis in short
Acinic cell carcinoma. H&E stain.
LM	"acinic cells" (abundant finely vacuolated cytoplasm with basophilic granules, small nuclei with stippled chromatin), scattered "intercalcated duct type cells" (eosinophilic cytoplasm with moderate amount of cytoplasm and bland nuclei), +/-peri-tumoural lymphocytes, +/-glassy extracellular bluish/purple blobs
Subtypes	oncocytic variant, clear cell variant, papillary cystic variant
LM DDx	oncocytoma of the salivary gland, mucoepidermoid carcinoma, adenocarcinoma NOS, secretory carcinoma of the salivary gland
Stains	PAS +ve, PASD +ve
IHC	p63 -ve, S-100 -ve
EM	zymogen granules
Gross	tan or reddish
Site	salivary gland - usu. parotid gland
Signs	salivary gland mass
Prevalence	uncommon
Prognosis	good

It should not to be confused with pancreatic acinar cell carcinoma.

General

• Malignant neoplasm of salivary gland arising from acinic cells.
• The relative prevalence of the neoplasm in the various salivary gland reflects the abundance of acinic cells: parotid gland (~80%) > minor salivary glands (~17%) > submandibular glands (~3%).
• Affects wide age range -- including children.
• Site affect prognosis (most aggressive to least aggressive): submandibular > parotid > minor salivary.
• Good prognosis - in one large cohort:
  • ~97% five year survival.
  • ~93% 10 year survival.

Gross

• Tan or reddish.

Microscopic

Features:

• Sheets of acinic cells with:
  • Abundant finely vacuolated cytoplasm with basophilic granules - key feature.
    • Granules may be focal.
  • Small nuclei stippled chromatin.
• Scattered intercalcated duct type cells with:
  • Eosinophilic cytoplasm with moderate amount of cytoplasm.
  • Bland nuclei with slightly larger than seen in acinic cells.
• +/-Peri-tumoural lymphocytes.
• +/-Glassy extracellular bluish/purple blobs.

Notes:

• Adipose tissue -- present in the salivary glands -- is absent in AcCC.
• May focally resemble thyroid tissue.
• Smaller (characteristic) microvacuoles (unreported in the literature) may be present that have a bubbly appearance and glassy basophilic inclusions.

Memory device:

• AcCC - lots of "C"s - chromatin stipled, cytoplasm generous.

DDx:

• Oncocytoma of the salivary gland.
• Adenocarcinoma not otherwise specified.
• Secretory carcinoma of the salivary gland (previously mammary analogue secretory carcinoma).

Images

Case

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  AcCC - intermed. mag. (WC/Nephron)

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  AcCC - high mag. (WC/Nephron)

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  AcCC - very high mag. (WC/Nephron)

Case

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  AcCC - low mag. (WC/Nephron)

• 

  AcCC - intermed. mag. (WC/Nephron)

• 

  AcCC - high mag. (WC/Nephron)

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  AcCC - very high mag. (WC/Nephron)

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  AcCC - very high mag. (WC/Nephron)

www

• AcCC (brown.edu).

Grading

General:

• Not prognostic.
• Done to avoid phone calls from clinician.

Factors Weinreb uses:

• Necrosis.
• Nuclear atypia.
• Perineural invasion.
• Mitoses.
• Infiltrative margin.
• Tumour sclerosis.

Subtypes

• Oncocytic variant - rare.
• Clear cell variant - rare.
• Papillary cystic variant.

Stains

• PAS +ve.
• PAS-D +ve.

IHC

• S-100 -ve.
• p63 -ve (30 -ve of 30 cases).
  • p63 +ve in mucoepidermoid carcinoma (24 +ve of 24 cases).

• NR4A3 +ve (nuclear).

There are a bunch of other stains that are touted to be useful (amylase, anti-chymotrypsin, lactoferrin). Weinreb thinks these are not helpful.

Molecular

• t(4;9)(q13;q31)

EM

• Zymogen granules.

Sign out

A. Tumour, Left Parotid Gland, Excision:
- ACINIC CELL CARCINOMA, see comment.
-- Margins clear.
-- Please see synoptic report.

B. Lymph Nodes, Left - Level 2 & 3, Lymphadenectomy:
- Five lymph nodes NEGATIVE for malignancy (0/5).

Comment:
Immunostains are in keeping with acinic cell carcinoma (mammaglobin, S-100 and p63 are all NEGATIVE). A PAS stain is positive in the tumour.

See also

• Salivary glands.