---
schema_version: "secwatch.filing_event.v1"
accession: "0001447362-21-000197"
form_type: "8-K"
ticker: "CSTL"
cik: "0001447362"
company_name: "CASTLE BIOSCIENCES INC"
filed_at: "2021-08-09T23:59:59+00:00"
generated_at: "2026-06-29T18:23:59.492764+00:00"
event_type: "earnings"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Castle Biosciences Q2 revenue $22.8M (+79% YoY); raises FY2021 guidance to $89-93M

## Summary
- Revenue $22.8M, up 79% YoY; adjusted revenue $22.9M, up 120% YoY excluding prior-period adjustments.
- DecisionDx-Melanoma test reports up 70% YoY to 5,128; total dermatology test volume 6,539.
- Full-year 2021 revenue guidance raised to $89-93M from prior $80-83M.
- Acquired Myriad myPath Laboratory for $33M in May, adding myPath Melanoma test.
- Cash at $368M; operating cash flow -$6.4M due to acquisition and Medicare advance recoupment.

## SEC filing metadata
- accession: 0001447362-21-000197
- form_type: 8-K
- ticker: CSTL
- cik: 0001447362
- company_name: CASTLE BIOSCIENCES INC
- filed_at: 2021-08-09T23:59:59+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/1447362/000144736221000197/0001447362-21-000197-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1447362/000144736221000197/cstl-20210809.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001447362-21-000197
- JSON: https://secwatch.observer/filing/0001447362-21-000197.json
- Plain text: https://secwatch.observer/filing/0001447362-21-000197.txt

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