---
schema_version: "secwatch.filing_event.v1"
accession: "0001628280-26-031255"
form_type: "8-K"
ticker: "CSTL"
cik: "0001447362"
company_name: "CASTLE BIOSCIENCES INC"
filed_at: "2026-05-06T23:59:59+00:00"
generated_at: "2026-05-14T22:36:00.162219+00:00"
event_type: "earnings"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Castle Biosciences Q1 revenue $83.7M; core tests +36%; raises FY guidance to $345-355M

## Summary
- Revenue $83.7M vs $88.0M Q1 2025; core test reports +36% YoY (DecisionDx-Melanoma +16%, TissueCypher +58%).
- Net loss improved to $14.5M ($0.49/share) from $25.8M ($0.90); adjusted EBITDA -$5.1M vs +$13.0M.
- Raises FY2026 revenue guidance to $345-355M from $340-350M; cash & investments $261.7M.
- Gross margin 73% (adj. 76%) vs 49% (adj. 81%) prior year, which included $20.1M amortization acceleration.
- Operating cash use $22.1M includes $28.8M in one-time bonus/benefit payments not expected to recur in 2026.

## SEC filing metadata
- accession: 0001628280-26-031255
- form_type: 8-K
- ticker: CSTL
- cik: 0001447362
- company_name: CASTLE BIOSCIENCES INC
- filed_at: 2026-05-06T23:59:59+00:00
- event_type: earnings
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 2.02, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1447362/000162828026031255/0001628280-26-031255-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1447362/000162828026031255/cstl-20260506.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001628280-26-031255
- JSON: https://secwatch.observer/filing/0001628280-26-031255.json
- Plain text: https://secwatch.observer/filing/0001628280-26-031255.txt

## Source-grounded claims
- claim_id: 80f28c725ee2a60c3a56d4a25937e90ba33d2685
  claim: CASTLE BIOSCIENCES INC reported first quarter ended March 31, 2026 results: revenue $83.7 million, net income $14.5 million, EPS $0.49. Guidance raised.
  evidence_excerpt: Castle Biosciences Reports First Quarter 2026 Results Delivered Q1 2026 revenue of $83.7 million
  evidence_url: https://www.sec.gov/Archives/edgar/data/1447362/000162828026031255/0001628280-26-031255-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.