Summary & Overview
CPT 21931: Excision of Soft-Tissue Tumor Back or Flank, 3 cm or Greater
CPT code 21931 represents the surgical excision of a soft-tissue tumor or abnormal mass of 3 cm or greater located beneath the skin of the back or flank, with submission of the specimen for pathological evaluation. This code captures a common oncologic and general surgical procedure used to diagnose and treat suspicious soft-tissue lesions; accurate coding affects clinical documentation, pathology processing, and payer reimbursement nationwide.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find guidance on the clinical context of the procedure, typical sites of service (hospital outpatient departments and ambulatory surgical centers), common modifier use (listed separately), and payer coverage considerations. The publication summarizes benchmarks and billing practice patterns, highlights documentation elements tied to pathology specimen submission, and outlines policy updates that influence claim adjudication and reimbursement for soft-tissue excisions.
This executive summary is intended to help coding professionals, surgical teams, and billing staff understand the clinical and administrative implications of CPT code 21931, improve claim accuracy, and anticipate payer requirements during preauthorization and claims submission.
Billing Code Overview
CPT code 21931 describes the surgical removal of a tumor or abnormal mass measuring 3 centimeters or larger from the soft tissues beneath the skin of the back or flank. The removed specimen is submitted for pathological analysis to evaluate for abnormal or malignant cells.
Service type: Surgical excision of soft tissue mass
Typical site of service: Hospital outpatient department or ambulatory surgical center, and may also occur in an inpatient surgical setting depending on clinical need.
Clinical & Coding Specifications
Clinical Context
A 58-year-old male presents to a general surgery clinic with a progressively enlarging, palpable soft-tissue mass in the left paraspinal region of the back. The lesion measures clinically and on imaging at approximately 4.2 cm. The patient reports intermittent discomfort and occasional local skin irritation but no systemic symptoms. Magnetic resonance imaging (MRI) of the lumbar soft tissues demonstrates a well-circumscribed subcutaneous soft-tissue mass deep to the dermis in the flank, suspicious for a lipomatous tumor versus sarcoma. The surgical team schedules an excisional biopsy under monitored anesthesia care (MAC). Intraoperative workflow includes preoperative verification, anesthesia induction, surgical site marking, sterile preparation, elliptical incision over the mass, dissection through subcutaneous tissue to the mass in the back/flank, complete excision of the lesion measuring greater than 3 cm, hemostasis, evaluation of margins, and layered wound closure. The specimen is labeled and sent to pathology for histologic examination and possible immunohistochemical studies to determine benign versus malignant etiology. Postoperative instructions include wound care, activity restrictions, and follow-up for pathology results and potential further oncologic referral if malignant features are identified.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the physician’s professional component for associated diagnostic services (rare for excision CPT itself). |