Acinic cell carcinoma

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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, mammary analogue secretory carcinoma
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

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

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:[1]
    • ~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.[2]

Memory device:

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

DDx:

Images

Case

  • AcCC - intermed. mag. (WC/Nephron)

  • AcCC - high mag. (WC/Nephron)

  • AcCC - very high mag. (WC/Nephron)

Case

  • AcCC - low mag. (WC/Nephron)

  • AcCC - intermed. mag. (WC/Nephron)

  • AcCC - high mag. (WC/Nephron)

  • AcCC - very high mag. (WC/Nephron)

  • AcCC - very high mag. (WC/Nephron)

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Grading

General:

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

Factors Weinreb uses:[2]

Subtypes

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

Stains

  • PAS +ve.
  • PAS-D +ve.

IHC

There are a bunch of other stains that are touted to be useful (amylase, anti-chymotrypsin, lactoferrin). Weinreb thinks these are not helpful.[2]

EM

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 (mammoglobin, S-100 and p63 are all NEGATIVE). A PAS stain is positive in the tumour.

See also

References

  1. ↑ Patel, NR.; Sanghvi, S.; Khan, MN.; Husain, Q.; Baredes, S.; Eloy, JA. (Jan 2014). "Demographic trends and disease-specific survival in salivary acinic cell carcinoma: an analysis of 1129 cases.". Laryngoscope 124 (1): 172-8. doi:10.1002/lary.24231. PMID 23754708.
  2. ↑ 2.0 2.1 2.2 IW. 11 January 2011.
  3. ↑ Ihrler, S.; Blasenbreu-Vogt, S.; Sendelhofert, A.; Lang, S.; Zietz, C.; Löhrs, U. (2002). "Differential diagnosis of salivary acinic cell carcinoma and adenocarcinoma (NOS). A comparison of (immuno-)histochemical markers.". Pathol Res Pract 198 (12): 777-83. PMID 12608654.
  4. ↑ Lei, Y.; Chiosea, SI. (Jun 2012). "Re-evaluating historic cohort of salivary acinic cell carcinoma with new diagnostic tools.". Head Neck Pathol 6 (2): 166-70. doi:10.1007/s12105-011-0312-9. PMID 22127547.
  5. ↑ 5.0 5.1 Sams, RN.; Gnepp, DR. (Mar 2013). "P63 expression can be used in differential diagnosis of salivary gland acinic cell and mucoepidermoid carcinomas.". Head Neck Pathol 7 (1): 64-8. doi:10.1007/s12105-012-0403-2. PMID 23054955.
  6. ↑ Sun, Y.; Wasserman, PG. (Feb 2004). "Acinar cell carcinoma arising in the stomach: a case report with literature review.". Hum Pathol 35 (2): 263-5. PMID 14991547.
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