#dermpathJC June 2017:

Thursday, June 29th, 9pm EST

Article discussed: “SOX10 immunohistochemistry in sweat ductal/glandular neoplasms.”

Authors: Cassarino D, Su A, Robbins B, Altree-Tacha D, Ra S.

Journal of Cutaneous Pathology, June 2017.

Free access at: tinyurl.com/sox10  for 2 months.

Special thanks to Dr Annie Morrison (@AnnieMorrisonMD) for providing the summary below.

Journal Club Summary:

Background: Sox10 is a relatively new IHC stain that is used as a melanocytic and schwannian marker.

Prelim observation/previous study: Sox10 IHC positive in eccrine glands and negative in eccrine ducts, apocrine glands, and hair follicles

Hypothesis: Sweat gland tumors of suspected eccrine origin would show Sox10 expression while apocrine-derived sweat gland tumors would not.

Methods: 90 sweat gland tumors (all with classic histopathology) and 13 basal cell carcinomas evaluated:

Cylindroma 10

Spiradenoma 13

Syringocystademona papilliferum 10

Hidradenoma papilliferum 10

Poroma 12

Syringoma 10

Apocrine adenoma 10

Hidradenoma 15

Stain used: anti-Sox10 antibody (clone BC34: Biocare Medical,, Concord, California; dilution 1:20)

Stain evaluation: percentage of tumor cells (semiquantitative) and staining intensity (0, 1+, 2+, 3+) recorded.

Results Table:

Discussion highlights: Strong diffuse positivity for Sox10 in cylindroma and spiradenoma and the complete absence of Sox10 staining in BCC may be helpful in the setting of a small, superficially sampled, and/or poorly oriented or fragmented specimen.

Sox10 staining in SCAP and HAP: diffuse myoepithelial cell staining, not unexpected

Myoepithelial cells: + Sox10 in normal salivary glands & ducts, salivary gland tumors, breast lobules, cutaneous myoepitheliomas, and cutaneous mixed tumors with predominate myoepithelial components.

SCAP, HAP, and apocrine adenomas: focal + Sox10 in apocrine epithelial cells, unexpected

New hypothesis: Sox10 expression may be upregulated in a portion of the lesional cells

Poroma & syringomas: Sox10 negative, expected

Both believed to be derived from sweat ducts

Hidradenoma: heterogenous Sox10 staining; somewhat expected

Hidradenomas are heterogenous tumors, two cell types (clear cells & dark/eosinophilic cells)

Weak/negative Sox10 staining appeared more common in lesions/areas with clear cell predominance.

Limitations of study:

Small sample size

Limited lesions evaluated (another study planned to look at follicular tumors and adnexal carcinomas)

Twitter Journal Club Discussion Summary:

A significant number of #dermpathJC participants use Sox10 with or without S100protein to distinguish melanocytic/neural lesions from other lesions, and/or in sentinal lymph nodes for melanoma.

Sox10 has been used by some participants to evaluate adenoid cystic carcinoma

Sox10 is negative in PEComas, fibrohistiocytic and histiocytic proliferations.

A known Sox10 pitfall is occasional staining in scars, particularly concerning when evaluating desmoplastic melanomas.

From this paper Sox10 does not appear to help distinguish between eccrine and apocrine differentiation in adnexal lesions. Histomorphology is still the “gold standard”.

Study confirms: Sox10 stains myoepithelial cells in cutaneous adnexal lesions.

The results of the pending study of Sox10 expression in follicular tumors and adnexal carcinomas is of interest to many participants.

More studies/references are needed to further characterize Sox10 expression in adnexal lesions.

Diagram of Sox10 role in neural crest cell migration:

Fun fact: SOX10 aka SRY-related HMG-box. SOX10 gene expression regulated by MITF in melanocytic lesions.

Interesting Link: Music from SOX10 protein sequence: https://www.youtube.com/watch?v=rA126rgymAo

See y’all next month!