Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Oelschlager Kristen M 2. Issuer Name and Ticker or Trading Symbol CASTLE BIOSCIENCES INC [CSTL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) C/O CASTLE BIOSCIENCES, INC., 1500 W. PARKWOOD AVE SUITE 400 3. Date of Earliest Transaction (Month/Day/Year) 03/03/2026 (Street) FRIENDSWOOD, TX 77546 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/03/2026 F 2,427(1) D $27.57 20,068(2) D Common Stock 03/04/2026 M 25,771 A (3) 45,839 D Common Stock 03/04/2026 F 6,792 D $28.17 39,047 D Common Stock 97,251 I The Fritz Shorter Trust(4)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Units

(3)

03/03/2026

A

48,367

(5)

(5)

Common Stock

48,367

$ 0

48,367

D

Restricted Stock Units

(3)

03/04/2026

M

13,811

(6)

(6)

Common Stock

13,811

$ 0

27,621

D

Restricted Stock Units

(3)

03/04/2026

M

11,960

(7)

(7)

Common Stock

11,960

$ 0

35,878

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Oelschlager Kristen M C/O CASTLE BIOSCIENCES, INC. 1500 W. PARKWOOD AVE SUITE 400 FRIENDSWOOD, TX 77546			Chief Operating Officer

Signatures

/s/ Frank Stokes, Attorney-in-fact		03/05/2025
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Reflects the withholding of shares of the Issuer's common stock to satisfy tax withholding obligations in connection with the delivery of vested performance stock units reported on January 12, 2026.
(2)	Includes 965 shares acquired on February 27, 2026, under the Issuer's employee stock purchase plan.
(3)	Each Restricted Stock Unit ("RSU") represents the right to receive one share of the Issuer's Common Stock.
(4)	Held by the Fritz Shorter Trust of which the Reporting Person and her spouse are the trustees and beneficiaries.
(5)	The RSU's vest in four equal annual installments beginning on March 03, 2027.
(6)	On March 4, 2024, the Reporting Person was granted 55,243 RSUs which vest in four equal installments beginning on March 4, 2025.
(7)	On March 4, 2025, the Reporting Person was granted 47,838 RSUs which vest in four equal installments beginning on March 4, 2026.

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