Immunohistochemistry S100 Test
Short Name: IHC S100
Also known as: S100 IHC Test, S100 Protein Immunohistochemistry, S100 Immunostain, IHC for S100, S100 Tissue Marker Test
Immunohistochemistry S100 Test test available at DNA Labs India for ₹3,000. Uses Immunohistochemistry on Tumor tissue in 10% Formal-saline OR Formalin fixed paraffin embedded (FFPE) block samples. Results in Sample daily by 6 PM. Report delivery: FFPE Block – 5 working days, Tissue Biopsy – 5 working days, Large/Complex Tissue – 7 working days.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr Pasupathy Arumugam
Consultant Pathologist · Reg: 21521
Last reviewed: September 7, 2026
Overview
The primary purpose of the Immunohistochemistry S100 test is to identify the S100 protein in tissue samples, aiding in the differential diagnosis of melanocytic lesions, neural tumours, and soft tissue neoplasms. It helps pathologists distinguish between benign and malignant lesions and supports treatment decision-making in oncology.
- Test Code
- 958
- CPT Code
- 88342
- ICD Code
- D48.5
- Price
- ₹3,000
- Sample Type
- Tumor tissue in 10% Formal-saline OR Formalin fixed paraffin embedded (FFPE) block
- Result Time
- Sample daily by 6 PM. Report delivery: FFPE Block – 5 working days, Tissue Biopsy – 5 working days, Large/Complex Tissue – 7 working days.
- Fasting Required
- No
- Method
- Immunohistochemistry
Sample Collection
No special preparation is required from the patient. The tissue specimen is typically obtained via biopsy or surgical excision performed by the treating physician.
Method: Tissue Biopsy / Surgical Excision (collected by treating physician)
Laboratory Analysis
Tissue is collected through incisional biopsy, excisional biopsy, or surgical resection by the referring specialist under appropriate anaesthesia and sterile conditions.
Report Delivery
The collected tissue is immediately placed in 10% neutral buffered formalin or submitted as an FFPE block. A copy of the histopathology report, site of biopsy, and clinical history must accompany the specimen.
Timeline: Sample daily by 6 PM. Report delivery: FFPE Block – 5 working days, Tissue Biopsy – 5 working days, Large/Complex Tissue – 7 working days.
Patient Instructions
About This Test
Who Should Get This Test
The primary purpose of the Immunohistochemistry S100 test is to identify the S100 protein in tissue samples, aiding in the differential diagnosis of melanocytic lesions, neural tumours, and soft tissue neoplasms. It helps pathologists distinguish between benign and malignant lesions and supports treatment decision-making in oncology.
How to Prepare
- Submit tumour tissue in 10% Formal-saline or as a Formalin Fixed Paraffin Embedded (FFPE) block
- Ship the specimen at room temperature
- Provide a copy of the Histopathology report along with the sample
- Mention the exact site of biopsy on the requisition form
- Include relevant clinical history and provisional diagnosis
- Ensure proper labelling of the container with patient details
Doctor's Notes
Reviewed by Dr Pasupathy Arumugam — MBBS, MD (Pathology) · Reg. No. 21521
"S100 immunohistochemistry is a critical ancillary marker in the evaluation of melanocytic tumors, nerve sheath tumors, and various soft tissue neoplasms. It should always be interpreted in the context of morphology and a panel of other immunohistochemical markers rather than in isolation. A positive S100 result does not confirm malignancy on its own and must be correlated with clinical, histopathological, and radiological findings by a qualified pathologist and treating oncologist."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Tissue received without formalin fixation and beyond 30 minutes of collection
- Specimen without proper patient identification or labelling
- Sample without accompanying histopathology report or clinical history
- Severely autolysed or necrotic tissue unsuitable for interpretation
- Specimen received in leaked or contaminated container
Understanding Your Results
S100 Positive (Strong, Diffuse)
Strong and diffuse S100 positivity is commonly seen in melanoma, schwannoma, and neurofibroma. Correlation with additional markers such as HMB-45, Melan-A, SOX10, and Ki-67 is recommended for definitive diagnosis.
S100 Positive (Focal/Moderate)
Focal or moderate positivity may be seen in a variety of benign and malignant soft tissue tumours. Further workup with a broader immunohistochemical panel and clinical correlation is advised.
S100 Negative
A negative S100 result does not entirely exclude melanocytic or neural tumours, as some variants may lose S100 expression. Additional markers and histopathological review should be performed.
Inconclusive / Weak Staining
Weak or equivocal staining may result from suboptimal fixation, antigen degradation, or biological variability. Repeat testing or alternative markers may be considered.
You should consult your treating physician or oncologist if you have a new or changing skin lesion, an unexplained lump, a mole that has changed in colour, size, or shape, or if your histopathology report requires further characterisation. Early consultation is essential for timely diagnosis and management.
Limitations
- ⚠S100 is not entirely specific to melanoma; it is also positive in Schwann cells, dendritic cells, chondrocytes, and adipocytes
- ⚠A positive S100 result alone does not confirm malignancy and must be interpreted alongside other IHC markers and clinical findings
- ⚠Some melanomas may lose S100 expression, particularly desmoplastic or metastatic variants, potentially leading to false negatives
- ⚠This test is supplementary to histopathological examination and does not replace a complete diagnostic workup
- ⚠Results may vary with different antibody clones and laboratory protocols
Risks & Considerations
- ●This test itself carries no risk as it is performed on an already collected tissue specimen
- ●The biopsy or surgical procedure to collect tissue carries standard procedural risks such as bleeding, infection, or discomfort at the site, which are managed by the treating physician
Interfering Factors
- ●Prolonged fixation in formalin may reduce antigenicity and cause false-negative staining
- ●Inadequate or delayed fixation can affect protein preservation
- ●Decalcification of bony tissue specimens may degrade S100 antigen
- ●Necrotic or heavily haemorrhagic tissue may yield unreliable results
- ●Previously treated (post-chemotherapy/radiation) specimens may show altered expression
Compare With Similar Tests
| Test | Immunohistochemistry S100 Test | HMB-45 (Melanoma Marker) | Melan-A / MART-1 | SOX10 | Vimentin |
|---|---|---|---|---|---|
| Comparison | Immunohistochemistry S100 Test |
Frequently Asked Questions
What is the Immunohistochemistry S100 test?
Why has my doctor ordered the S100 IHC test?
What type of sample is needed for this test?
Does a positive S100 result mean I have cancer?
What is the cost of the Immunohistochemistry S100 test at DNA Labs India?
How long does it take to get the S100 test results?
Is home sample collection available for the S100 test?
What other tests may be needed along with the S100 test?
Can the S100 test differentiate between benign and malignant tumours?
Are there any risks associated with the S100 test?
Is the Immunohistochemistry S100 test covered by insurance?
Where can I get the Immunohistochemistry S100 test done?
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