Salivary duct carcinoma

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Salivary duct carcinoma, abbreviated SDC, is a rare salivary gland tumour that typically has an aggressive course.

Salivary duct carcinoma
Diagnosis in short

Salivary duct carcinoma. H&E stain.

LM varied arch. (sheets, nests, cords, cribriform, micropapillary), neoplastic cells line-up around cystic spaces "Roman bridges", nuclear atypia, apocrine snouts, decapitation secretions
LM DDx Carcinoma ex pleomorphic adenoma with SDC component, ductal carcinoma of the breast
Site salivary gland

Prognosis poor
Clin. DDx other salivary gland tumours

General

  • Malignant counterpart of salivary duct adenoma.
  • Male:female ~= 4:1.
  • Dismal prognosis.[1]
  • Typically >50 years old.
  • Mostly in the parotid.

Microscopic

Features - resembles ductal breast carcinoma:[1]

  • Architecture: sheets, nests, cords, cribriform, micropapillary.
  • Neoplastic cells line-up around cystic spaces "Roman bridges".
  • Nuclear atypia (variation in size, shape, staining).
  • Apocrine snouts - pseudopod-like/lollipop-like undulations of the cell membrane.
  • Decapitation secretions - apocrine snouts (membrane bound blobs of cytoplasm) that have separated from its mother cell.

Notes:

  • Similar to ductal breast carcinoma - key to remember.

DDx:

Images

www:

Subtypes

  • Conventional.
  • Mucinous - worse prognosis; opposite of what would one expect from the outcomes in breast cancer.
  • Micropapillary - assoc. with a poor prognosis.
  • Sarcomatoid/spindle cell.

IHC

  • LMWK, EMA, CK7, CK19 +ve.
  • p63 -ve.
  • Androgen receptor +ve.
  • BRST2 (GCDFP-15) +ve.
  • HER2 +ve ~21%; use of trastuzumab (Herceptin) not systematically studied.

Curiosity:

  • PSA +/-.
  • PSAP +/-.
  • ER-beta +ve.[2]
  • ER-alpha -ve (the common ER stain).

See also

References