---
schema_version: "secwatch.filing_event.v1"
accession: "0001447362-21-000250"
form_type: "8-K"
ticker: "CSTL"
cik: "0001447362"
company_name: "CASTLE BIOSCIENCES INC"
filed_at: "2021-11-08T23:59:59+00:00"
generated_at: "2026-06-28T11:24:13.174824+00:00"
event_type: "earnings"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Castle Q3 revenue $23.5M (+54% YoY); guides FY21 $89-93M; acquiring Cernostics

## Summary
- Q3 revenue $23.5M, up 54% vs $15.2M in Q3 2020; adjusted revenue $23.6M, up 71%.
- Total test reports 7,727 (vs 4,779); DecisionDx-Melanoma 5,505 (+25%), DecisionDx-SCC 934.
- Gross margin 77.9%; adjusted 80.9%; cash $363M as of Sept 30, 2021.
- Signed definitive agreement to acquire Cernostics (TissueCypher BE test) to expand TAM by ~$1B; close expected by year-end 2021.
- On track to meet raised FY21 revenue guidance of $89-93M.

## SEC filing metadata
- accession: 0001447362-21-000250
- form_type: 8-K
- ticker: CSTL
- cik: 0001447362
- company_name: CASTLE BIOSCIENCES INC
- filed_at: 2021-11-08T23:59:59+00:00
- event_type: earnings
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 2.02, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1447362/000144736221000250/0001447362-21-000250-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1447362/000144736221000250/cstl-20211108.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001447362-21-000250
- JSON: https://secwatch.observer/filing/0001447362-21-000250.json
- Plain text: https://secwatch.observer/filing/0001447362-21-000250.txt

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