Stains
S100

Author: Nat Pernick, M.D. (see Authors page)

Revised: 18 December 2015, last major update January 2013

Copyright: (c) 2002-2015, PathologyOutlines.com, Inc.

PubMed Search: S-100 [title]

Definition / General
  • Acidic protein, 100% Soluble in ammonium sulfate at neutral pH (derivation of name)
  • S100 protein family is multigenic group of nonubiquitous cytoplasmic EF-hand Ca2+-binding proteins, sharing significant structural similarities at both genomic and protein levels; S100 protein family has 24 known human members each coded by a separate gene; at least 19 on chromosome 1q21 (Hepat Mon 2012;12:e7240)
  • Helps regulate cell contraction, motility, growth, differentiation, cell cycle progression, transcription and secretion
  • Structurally similar to calmodulin
Interpretation
  • Cytoplasmic and nuclear staining usually required to call positive
Uses by Pathologists
  • Common marker of neural tissue / lesions and melanoma
  • Differentiate plexiform schwannoma (S100+, Am J Surg Pathol 2005;29:1042) from MPNST (weak / negative / patchy)
  • MelanA and MART1 appear to be superior to S100 for evaluating sentinel lymph nodes for melanoma (Am J Surg Pathol 2001;25:1039)
Micro Images

Images hosted on PathOut server:
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Bladder: paraganglioma and paraganglioma-site unspecified

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Breast: granular cell tumor

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Breast: metaplastic carcinoma

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Lymph nodes: mycobacterial spindle cell pseudotumor

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Salivary gland: epithelial myoepithelial carcinoma

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Soft tissue: plexiform schwannoma

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Skin: Langerhans cell histiocytosis-tumor cells are strongly S100+


Flickr mages:
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Breast: basal-like invasive ductal carcinoma
(has S100+ myoepithelial phenotype)
c/o Dr. Semir Vranic

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Breast: Paget's disease is S100-
c/o Dr. Semir Vranic


Images hosted on other servers:
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Quality control images (various)

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Adrenal gland: pheochromocytoma-sustentacular cells are S100+

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Bladder: paraganglioma and paraganglioma-site unspecified

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Breast: liposarcoma - lipoblasts are S100+ (figure 4)

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Breast: malignant adenomyoepithelioma - S100+ in benign areas

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Cervix: plexiform neurofibroma and Pacinian corpuscles are S100+ (figures 3/4)

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CNS: Rosai-Dorfman

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Colon: schwannoma

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Heart: granular cell tumor

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Lymph nodes: Omenn's syndrome - interdigitating reticulum cells are S100+

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Oral cavity: S100 demonstrates perineural invasion in squamous cell carcinoma (fig 2B)

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Prostate: sclerosing adenosis

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Skin: granular cell tumor

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Skin: melanoma, desmoplastic

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Soft tissue: arteriovenous vascular malformation has small nerve bundle that is S100+

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Soft tissue: chondrosarcoma

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Soft tissue: MPNST

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Testis: Large cell calcifying Sertoli cell tumor


Images hosted on Nature.com:
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CNS: Rosai-Dorfman

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Larynx: granular cell tumor

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Nasal cavity: olfactory neuroblastoma

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Skin: melanoma and nevus cells

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Testis: Cowden's syndrome patient has S100+ adipocytes

Positive Staining - Normal
  • Neural crest derived tissue: Schwann cells, melanocytes, glial cells
  • Skin apocrine and eccrine glands
  • Adipocytes, chondrocytes, dendritic cells, Langerhans cells, macrophages, myoepithelial cells
  • Some breast epithelial cells
Positive Staining - Disease
  • Adenoid cystic carcinoma
  • Chondroid tumors
  • Chordoma
  • Clear cell sarcoma
  • Dendritic cell tumors
  • Glial tumors
  • Granular cell tumor (Arch Pathol Lab Med 2004;128:771)
  • Langerhans cell tumors
  • Lipogenic tumors
  • Malignant peripheral nerve sheath tumor (50%)
  • Melanoma (95%, including desmoplastic and spindle cell tumors); S100- melanomas often had prior S100+ metastases, often are ocular (Hum Pathol 2005;36:1016)
  • Mycobacterial spindle cell pseudotumor in lymph nodes
  • Myoepithelial tumors
  • Neural tumors
  • Paragangliomas: sustentacular cells
  • Perivascular epithelioid cell tumors (angiomyolipoma, clear cell "sugar" tumor, lymphangioleiomyomatosis, PEComas)
  • Rosai-Dorfman disease
  • Sex cord stromal tumors
Negative Staining
  • Fibroblasts, fibroblastic reticulum cells, perineural cells
  • Atypical fibroxanthoma
  • Cardiac sarcomas
  • Myofibroblastoma
  • Solitary fibrous tumor
  • Xanthoma