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chondroid syringoma

Wednesday 25 July 2012

Malignant Cutaneous Mixed Tumor

PO

Definition: Cutaneous mixed tumor (chondroid syringoma) is the cutaneous counterpart of pleomorphic adenoma of salivary glands, comprised of both epithelial and mesenchymal components. Malignant transformation is exceptionally rare, with only a few cases reported.

Mixed tumor/chondroid syringoma which is characterized by PLAG1 gene rearrangement.

Images

- Chondroid syringoma

- Malignant mixed tumor arising in chondroid syringoma : perineural invasion, mitosis

Differential diagnosis

- salivary mixed tumors
- malignant chondroid syringoma

- apocrine tumors

  • apocrine mixed tumor: has characteristic decapitation secretion
  • other adnexal tumors with apocrine differentiation

- chondroid tumors

  • cutaneous chondroma: lacks the epithelial and myoepithelial elements

- mixed tumors
- * malignant mixed tumor: necrosis, infiltrative growth, marked pleomorphism and greater cellularity

- metastatic carcinoma: can often be distinguished based on immunohistochemistry and cytologic features of malignancy

- parachordoma: rare, no true ducts, actin negative, presence of physalliferous cells, arises adjacent to tendon and synovium in extremities

  • often considered a variant of myoepithelioma

- collagenous spherulosis: more common in breast, lumina contain dense eosinophilic secretion, no biphasic appearance

- hidradenoma papilliferum: no chondroid matrix, not biphasic

- myopeithelioma / adenomyoepithelioma of the skin: more common on extremities, myoepithelial areas should predominate, lacks luminal epithelial cells, negative for cytokeratin and CEA

See also

- cutaneous apocrine tumors
- mixed tumors
- syringoma

Open references

- Myoepithelial neoplasms of soft tissue: an updated review of the clinicopathologic, immunophenotypic, and genetic features. Jo VY, Fletcher CD. Head Neck Pathol. 2015 Mar;9(1):32-8. doi : 10.1007/s12105-015-0618-0
PMID: 25804378 (Free)