CASTLE BIOSCIENCES INC (CSTL)

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of financial condition and results of operations together with our unaudited condensed consolidated financial statements and the related notes and other financial information included in this Quarterly Report on Form 10-Q with our audited financial statements and notes thereto as of and for the years ended December 31, 2025, and 2024 and the related Management’s Discussion and Analysis of Financial Condition and Results of Operations, including the section entitled “Critical Accounting Estimates,” included in our Annual Report on Form 10-K for the year ended December 31, 2025 (the “2025 10-K”), as filed with the Securities and Exchange Commission (the “SEC”) on February 26, 2026. Unless the context requires otherwise, references in this Quarterly Report on Form 10-Q to “we,” “us” and “our” refer to Castle Biosciences, Inc.

Forward-Looking Statements

The information in this discussion contains forward-looking statements and information within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), which are subject to the “safe harbor” created by those sections. These forward-looking statements include, but are not limited to, statements concerning our strategy, future operations, future financial position, future revenues, projected costs, prospects and plans and objectives of management. The words “anticipate,” “believe,” “could”, “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “project,” “will,” “would” or the negative or plural of these terms or other similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions or expectations disclosed in the forward-looking statements that we make. These forward-looking statements involve risks and uncertainties that could cause our actual results to differ materially from those in the forward-looking statements, including, without limitation, the risks set forth in Part I, Item 1A, “Risk Factors” in the 2025 10-K, Part II, Item 1A, “Risk Factors” in this Quarterly Report on Form 10-Q and in our other filings with the SEC. The forward-looking statements are applicable only as of the date on which they are made, and we do not assume any obligation to update any forward-looking statements, except as may be required by law.

Overview

Castle Biosciences, Inc. is a molecular diagnostics company offering innovative test solutions to aid clinicians in the diagnosis and treatment of dermatologic cancers, Barrett’s esophagus (“BE”), atopic dermatitis (“AD”), and uveal melanoma (“UM”).

Our Test Portfolio

We currently offer six commercially available proprietary multi-analyte assays with algorithmic analysis (“MAAA”) tests for use in the fields of dermatology, gastroenterology, ophthalmology, and most recently includes a test to guide systemic treatment decisions in moderate-to-severe atopic dermatitis.

Our revenue is primarily generated by our DecisionDx-Melanoma risk stratification test for cutaneous melanoma (“CM”) and our TissueCypher risk stratification test for BE.

All of our MAAA tests, excluding our recently launched AdvanceAD-Tx test, have been granted Advanced Diagnostic Laboratory Test (“ADLT”) status by the Centers for Medicare and Medicaid (“CMS”) which means each test has demonstrated that (i) when combined with an empirically derived algorithm, it yields a result that predicts the probability a specific individual patient will develop a certain condition or conditions, or will respond to a particular therapy or therapies; and (ii) it provides new clinical diagnostic information that cannot be obtained from any other test or combination of tests. We believe this designation not only demonstrates our focus on developing and validating innovative tests but also enables our Medicare reimbursement rate to be set, over the long term, by the median private payor rate, which we believe provides a fair exchange of value. Further information about Medicare coverage and ADLT status with respect to each of our tests is set forth below.

Test Overview

Our Dermatology Tests

DecisionDx-Melanoma is our proprietary risk stratification gene expression profile (“GEP”) test designed to predict the likelihood of a positive sentinel lymph node and the risk of metastasis or recurrence for patients diagnosed with invasive CM. In a typical year, we estimate that approximately 130,000 patients are diagnosed with invasive CM in the U.S., representing an estimated U.S. total addressable market (“TAM”) of approximately $540 million. We estimate that approximately 50% of patients diagnosed with CM are 65 years of age or older.

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AdvanceAD-Tx is a non-invasive GEP test designed to guide systemic treatment selection for patients aged 12 years and older with moderate-to-severe AD. The test evaluates the expression of 487 genes across 12 known immune, inflammatory and skin-related pathways to identify the underlying biology driving an individual patient’s disease. Results classify patients into one of two molecular profiles: Janus Kinase (“JAK”) Inhibitor Responder Profile or T helper 2 (“Th2”) Molecular Profile. Using multiple data sources focused on one-year prevalence, we estimate that there are approximately 10 million individuals ages 12 and older in the U.S. with moderate-to-severe AD, representing an estimated U.S. TAM of approximately $33 billion. We commenced a limited access launch of the AdvanceAD-Tx test in November 2025.

DecisionDx‑SCC is our proprietary GEP test for use in patients with SCC with one or more risk factors (also referred to as “high-risk” SCC) that both predicts the risk of metastasis as well as response to adjuvant radiation therapy. We estimate 20% of SCC patients, or approximately 200,000 annually in the U.S., are classified as high risk, representing an estimated U.S. TAM of approximately $820 million.

MyPath Melanoma is our proprietary, diagnostic GEP test for use in patients with difficult-to-diagnose melanocytic lesions. Of the 2 million suspicious pigmented lesions biopsied annually in the U.S., we estimate that approximately 300,000 of those present difficult-to-diagnose melanocytic lesion, representing an estimated U.S. TAM of approximately $600 million.

Our Gastroenterology Tests

TissueCypher is our proprietary risk stratification spatialomics test designed to predict future development of high-grade dysplasia (“HGD”) and/or esophageal cancer in patients with non-dysplastic (“ND”), indefinite dysplasia (“IND”) or low-grade dysplasia (“LGD”) BE. We estimate a U.S. TAM of approximately $1 billion. In May 2025, we expanded our BE capabilities through the acquisition of Capsulomics, Inc., d/b/a Previse (“Previse”), which includes methylation-based intellectual property and the Esopredict risk-stratification test. We expect these assets to support the future development of TissueCypher and enable the potential incorporation of additional molecular modalities. Beginning in the first quarter of 2026, we began offering Esopredict as a supplemental option when TissueCypher does not produce an actionable result. Revenue and test volume from Esopredict have not been material to date.

Our Ophthalmology Test

DecisionDx-UM is our proprietary, risk stratification GEP test that predicts the risk of metastasis for patients with UM. We believe DecisionDx-UM is the standard of care in the management of newly diagnosed UM in the majority of ocular oncology practices in the United States. We estimate a U.S. TAM of approximately $10 million.

Reimbursement

The primary source of revenue for our products is reimbursement from third-party payors, which includes government payors, such as Medicare, and commercial payors, such as insurance companies. Achieving broad coverage and reimbursement of our current products by third-party payors and continued Medicare coverage are key components of our financial success.

We bill third-party payors and patients for the tests we perform. We have received Medicare coverage for our DecisionDx-Melanoma, TissueCypher, MyPath Melanoma and DecisionDx-UM tests which meet certain criteria for Medicare and Medicare Advantage beneficiaries. DecisionDx-SCC previously received Medicare coverage, which was subsequently impacted by LCD changes finalized in 2025.

The Medicare rates discussed below are prior to giving effect to applicable sequestration in effect from time to time as described in further detail under “Government Regulation and Product Approval—Healthcare Reform” included in Item 1, Business, of the 2025 10-K.

DecisionDx-Melanoma

DecisionDx-Melanoma tests are processed from our Phoenix laboratory and since the second quarter of 2022, have been covered under “foundational” local coverage determinations (“LCD” or “LCDs”) finalized by Medicare Administrative Contractors (“MACs”) Palmetto and Noridian.

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CMS reviewed and approved DecisionDx-Melanoma for ADLT status in 2019. Our rate is set annually based upon the median private payor rate for the first half of the second preceding calendar year. For example, the rate for 2026 was set using median private payor rate data from January 1, 2024 to June 30, 2024. Our rate for 2024 and 2025 was $7,193 per test and remains $7,193 per test for 2026.

TissueCypher

Our TissueCypher tests are processed in our Phoenix and Pittsburgh laboratories. Palmetto’s MolDX program oversees MAAA tests that are reported from our Phoenix laboratory and Noridian is the MAC responsible for administering Medicare claims for test reports issued by our Phoenix laboratory. Novitas is the MAC responsible for administering Medicare claims for test reports issued by our Pittsburgh laboratory.

CMS reviewed and approved TissueCypher for ADLT status in 2022. Effective January 1, 2023, the published Clinical Laboratory Fee Schedule (“CLFS”) rate for TissueCypher was set at $4,950 per test and remained effective through December 31, 2024. This rate was based on the median private payor rates received between April 1, 2022 and August 31, 2022. Beginning with 2025, the rate for TissueCypher has been set annually based on the median private payor rate for the first half of the second preceding calendar year. The rate for 2026 was set using median private payor rate data from January 1, 2024 to June 30, 2024. Our rate for 2025 was $4,950 per test and remains $4,950 per test for 2026.

DecisionDx‑SCC

We issue our DecisionDx-SCC tests from our Pittsburgh and Phoenix laboratories. Palmetto’s MolDX (“MolDX”) program oversees MAAA tests that are reported from our Phoenix laboratory and Noridian is the MAC responsible for administering Medicare claims for test reports issued by our Phoenix laboratory. Novitas is the MAC responsible for administering Medicare claims for test reports issued by our Pittsburgh laboratory.

CMS reviewed and approved DecisionDx-SCC for ADLT status in 2023. Effective July 1, 2023 and through March 31, 2024, CMS set the initial period rate equal to the list price of $8,500 per test. Effective April 1, 2024, we continued receiving reimbursement at a rate of $8,500 per test, set by CMS using median private payor rate data for the period July 1, 2023 and November 30, 2023, and this rate remained effective through December 31, 2025. Our rate for 2025 was $8,500 per test and remains $8,500 per test for 2026.

On July 4, 2024, Palmetto and Noridian finalized an LCD recommending no coverage for Decisio

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Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of financial condition and results of operations together with our consolidated financial statements and the related notes included elsewhere in this Annual Report on Form 10-K. This discussion and other parts of this Annual Report on Form 10-K contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results, performance or achievements could differ materially from any future results, performance or achievements discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed under the heading “Special Note Regarding Forward-Looking Statements” and “Risk Factors.”

The following generally compares our results of operations for the years ended December 31, 2025 and 2024. A detailed discussion comparing our results of operations for the years ended December 31, 2024 and 2023 can be found in Part II, Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on February 27, 2025.

Overview

Castle Biosciences is a molecular diagnostics company offering innovative test solutions to aid clinicians in the diagnosis and treatment of dermatologic cancers, Barrett’s esophagus (“BE”), atopic dermatitis (“AD”), and uveal melanoma (“UM”).

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Our Test Portfolio

We currently offer six commercially available proprietary multi-analyte assays with algorithmic analysis (“MAAA”) tests for use in the fields of dermatology, gastroenterology and ophthalmology, and most recently includes a test to guide systemic treatment decisions in moderate-to-severe atopic dermatitis.

Our revenue is primarily generated by our DecisionDx-Melanoma risk stratification test for cutaneous melanoma (“CM”), our TissueCypher risk stratification test for BE which is supplemented by revenue generated from our DecisionDx-SCC risk stratification test for cutaneous squamous cell carcinoma (“SCC”), and our DecisionDx-UM risk stratification test for UM.

All of our MAAA tests, excluding our recently launched AdvanceAD-Tx test, have been granted Advanced Diagnostic Laboratory Test (“ADLT”) status by the Centers for Medicare and Medicaid (“CMS”) which means each test has demonstrated that (i) when combined with an empirically derived algorithm, it yields a result that predicts the probability a specific individual patient will develop a certain condition or conditions, or will respond to a particular therapy or therapies; and (ii) it provides new clinical diagnostic information that cannot be obtained from any other test or combination of tests. We believe this designation not only demonstrates our focus on developing and validating innovative tests but also enables our Medicare reimbursement rate to be set, over the long-term, by the median private payor rate, which we believe provides a fair exchange of value. Further information about Medicare coverage and ADLT status with respect to each of our tests is set forth below.

Test Overview

Our Dermatology Tests

DecisionDx-Melanoma is our proprietary risk stratification gene expression profile (“GEP”) test designed to predict the likelihood of a positive sentinel lymph node and the risk of metastasis or recurrence, for patients diagnosed with invasive CM. In a typical year, we estimate approximately 130,000 patients are diagnosed with invasive CM in the U.S., representing an estimated U.S. total addressable market (“TAM”) of approximately $540 million. We estimate that approximately 50% of patients diagnosed with CM are 65 years of age or older.

AdvanceAD-Tx is a non-invasive GEP test designed to guide systemic treatment selection for patients aged 12 years and older with moderate-to-severe atopic dermatitis (“AD”). The test evaluates the expression of 487 genes across 12 known immune, inflammatory and skin-related pathways to identify the underlying biology driving an individual patient’s disease. Results classify patients into one of two molecular profiles: Janus Kinase (“JAK”) Inhibitor Responder Profile or T helper 2 (“Th2”) Molecular Profile. Using multiple data sources focused on one-year prevalence, we estimate there are approximately 10.0 million individuals ages 12 and older in the U.S. with moderate-to-severe AD, representing an estimated U.S. TAM of approximately $33 billion. We commenced a limited access launch of the AdvanceAD-Tx test in November 2025.

DecisionDx‑SCC is our proprietary GEP test for use in patients with SCC with one or more risk factors (also referred to as “high-risk” SCC) that both predicts the risk of metastasis as well as response to adjuvant radiation therapy. We estimate 20% of SCC patients, or approximately 200,000 annually in the U.S., are classified as high risk, representing an estimated U.S. TAM of approximately $820 million.

MyPath Melanoma is our proprietary, diagnostic GEP test for use in patients with difficult-to-diagnose melanocytic lesions. Of the 2 million suspicious pigmented lesions biopsied annually in the U.S., we estimate approximately 300,000 of those present difficult-to-diagnose melanocytic lesion, representing an estimated U.S. TAM of approximately $600 million.

Our Gastroenterology Test

TissueCypher is our proprietary risk stratification spatialomics test designed to predict future development of high-grade dysplasia (“HGD”) and/or esophageal cancer in patients with non-dysplastic (“ND”), indefinite dysplasia (“IND”) or low-grade dysplasia (“LGD”) BE. We estimate a U.S. TAM of approximately $1 billion.

Our Ophthalmology Test

DecisionDx-UM is our proprietary, risk stratification GEP test that predicts the risk of metastasis for patients with UM. We believe DecisionDx-UM is the standard of care in the management of newly diagnosed UM in the majority of ocular oncology practices in the United States. We estimate a U.S. TAM of approximately $10 million.

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Our Mental Health Test

IDgenetix was a pharmacogenomic (“PGx”) test that guided personalized mental health medication selection and management for patients with depression, anxiety and other mental health conditions. We discontinued IDgenetix in May 2025 following further evaluation.

Commercial Expansion Efforts

During the year ended December 31, 2024, we further expanded our dermatology and gastroenterology teams. In late 2024, we changed our commercial strategy for our IDgenetix test, shifting resources to inside sales and non-personal promotion.

During the year ended December 31, 2025, we made several strategic acquisitions and partnerships to expand our clinical capabilities and product portfolio. In May 2025, we acquired Previse. This acquisition was intended to expand our GI diagnostic offerings beyond our existing TissueCypher test, representing a growth strategy through acquisition as well as organic product expansion. In June 2025, we entered into a collaboration and license agreement with SciBase to develop a diagnostic test aimed at predicting disease flares in patients with atopic dermatitis. In November 2025, we launched AdvanceAD-Tx, a new gene expression profile test designed to guide systemic treatment decisions for patients with moderate-to-severe AD. This launch represents a material expansion of our product portfolio into a significant new clinical area and a substantial potential market.

We will continue to assess market response in determining further commercial expansions and commercial team structure.

Reimbursement

The primary source of revenue for our products is reimbursement from third-party payors, which includes government payors, such as Medicare, and commercial payors, such as insurance companies. Achieving broad coverage and reimbursement of our current products by third-party payors and continued Medicare coverage are key components of our financial success.

We bill third-party payors and patients for the tests we perform. We have received Medicare coverage for our DecisionDx-Melanoma, TissueCypher, MyPath Melanoma, DecisionDx-UM and IDgenetix tests which meet certain criteria for Medicare and Medicare Advantage beneficiaries. DecisionDx-SCC previously received Medicare coverage, which was subsequently impacted by LCD changes finalized in 2025.

The Medicare rates discussed below are prior to giving effect to applicable sequestration in effect from time to time as described in further detail under “Government Regulation and Product Approval—Healthcare Reform” included in Item 1, Business, of this Annual Report on Form 10-K.

DecisionDx-Melanoma

DecisionDx-Melanoma tests are processed from our Phoenix laboratory and since the second quarter of 2022, have been covered under “foundational” local coverage determinations (“LCD” or “LCDs”) finalized by Medicare Administrative Contractors (“MACs”) Palmetto and Noridian.

DecisionDx-Melanoma has met ADLT status, as determined by the CMS, since 2019. Since 2022, the rate for DecisionDx-Melanoma is set annually based upon the median private payor rate for the first half of the second preceding calendar year. For example, the rate for 2025 was set using median private payor rate data from January 1, 2023 to June 30, 2023. Our rate for 2023 through 2025 was $7,193 per test and remains $7,193 per test for 2026.

TissueCypher

Our TissueCypher tests are processed in our Phoenix and Pittsburgh laboratories. Palmetto’s MolDX program oversees MAAA tests that are reported from our Phoenix laboratory and Noridian is the MAC responsible for administering Medicare claims for test reports issued by our Phoenix laboratory. Novitas is the MAC responsible for administering Medicare claims for test reports issued by our Pittsburgh laboratory.

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On March 24, 2022, CMS determined TissueCypher meets the criteria for “new ADLT” status. ADLT status exempts TissueCypher from what is called the “14-day rule,” which simplifies the billing process for Medicare patients. Effective January 1, 2023, the published CLFS rate for TissueCypher was set at $4,950 per test and remained effective through December 31, 2024. This rate is based on the median private payor rates received between April 1, 2022 and August 31, 2022. Beginning with 2025, the rate for TissueCypher has been set annually based on the median private payor rate for the first half of the second preceding calendar year. Our 2025 rate was $4,950 per test based on the median private payor rate data from January 1, 2023 to June 30, 2023 and remains $4,950 per test for 2026.

DecisionDx‑SCC

We issue our DecisionDx-SCC tests from our Pittsburgh and Phoenix laboratories. Palmetto’s MolDX (“MolDX”) program oversees MAAA tests that are reported from our Phoenix laboratory and Noridian is the MAC responsible for administering Medicare claims for test reports issued by our Phoenix laboratory. Novitas is the MAC responsible for administering Medicare claims for test reports issued by our Pittsburgh laboratory.

DecisionDx-SCC has met “new ADLT” status since 2023. Effective July 1, 2023 and through March 31, 2024, CMS set the initial period rate equal to the list price of $8,500 per test. Effective April 1, 2024, and through December 31, 2025, the published Clinical Laboratory Fee Schedule (“CLFS”) rate for DecisionDx-SCC will continue at $8,500 based on the median private payor rates received between July 1, 2023 and November 30, 2023.

On July 4, 2024, Palmetto and Noridian finalized an LCD recommending no coverage for DecisionDx-SCC with an effective date of August 18, 2024. On January 9, 2025, Novitas finalized an oncology biomarker LCD, Genetic Testing for Oncology: Specific Tests, which also lists DecisionDx-SCC as non-covered;

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