What is the ICD-10 (International Classification of Diseases, 10th Revision) code for a deep, firm, and mobile groin nodule that is not a cyst?

ICD-10 Coding for Deep, Firm, Mobile Groin Nodule (Non-Cystic)

For a deep, firm, mobile groin nodule that is explicitly not a cyst, the most appropriate ICD-10 code is R22.9 (Localized swelling, mass and lump, unspecified) or more specifically R22.1 (Localized swelling, mass and lump, neck) if you need anatomic specificity—though for groin location, R22.9 remains the standard code when the exact nature is undetermined.

Primary Coding Approach

• R22.9 is the default code for an unspecified localized mass or nodule when the pathologic diagnosis has not been established 1
• If the groin nodule has been biopsied or clinically characterized as a specific benign neoplasm, more specific codes should be used (D21.5 for benign neoplasm of connective tissue of pelvis) 1
• The code selection depends critically on whether tissue diagnosis has been obtained—clinical examination alone warrants R22.9 1

Differential Diagnostic Considerations That Affect Coding

Malignant Possibilities Requiring Different Codes:

• Lymph node metastasis from genitourinary malignancies (penile, vulvar, anal, or urethral cancers) would require C77.4 (Secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes) 2, 3
• Among patients with palpable inguinal nodes in the setting of known genitourinary malignancy, approximately 50% represent metastatic disease while 50% are inflammatory 3
• Physical examination characteristics matter: fixed inguinal nodal mass suggests cN3 disease in penile cancer staging, while mobile nodes suggest cN1-2 2

Benign Possibilities Requiring Specific Codes:

• Reactive lymphadenopathy (most common cause, 30-50% of palpable inguinal nodes) would use R59.9 (Enlarged lymph nodes, unspecified) 3
• Peripheral nerve sheath tumors (schwannoma/perineurioma) presenting as subcutaneous groin nodules would use D36.1 (Benign neoplasm of peripheral nerves and autonomic nervous system) after histologic confirmation 4
• Sebaceous neoplasms or other adnexal tumors would use D23.5 (Other benign neoplasm of skin of trunk) after biopsy 5

Clinical Features That Guide Code Selection

Key Physical Examination Findings to Document:

• Mobility status: Mobile nodes suggest cN1-2 staging in malignancy, while fixed masses suggest cN3 2
• Unilateral vs bilateral: Bilateral involvement suggests different staging and coding implications 2, 3
• Size measurement: Document largest diameter, as this affects management algorithms 2
• Consistency: Firm, deep nodules are less likely to be simple cysts (which would use different codes) 6

Imaging Characteristics That Refine Coding:

• Ultrasound findings of intact fatty hilum with cortical thickness <4mm suggest benign reactive nodes 3
• Loss of fatty hilum and cortical thickening >4mm raise concern for metastatic involvement 3
• If imaging confirms solid mass without cystic features, this supports R22.9 coding 2

Common Coding Pitfalls to Avoid

• Do not use cyst codes (N50.3 for spermatocele, N94.89 for other specified conditions of female genital organs) when the clinical description explicitly states "not a cyst" 6
• Avoid premature specific neoplasm coding without histologic confirmation—R22.9 is appropriate until tissue diagnosis is obtained 1
• Do not code as lymphadenopathy (R59.x) if the nodule is clearly not a lymph node based on location and characteristics 3
• Check for bilateral involvement before finalizing the code, as this may require additional codes or different staging codes in malignancy contexts 2

When to Use Alternative Codes

• If sentinel lymph node biopsy is performed and shows metastatic disease, transition to C77.4 2
• If fine-needle aspiration confirms specific benign pathology, use the appropriate D-code (D21.5 for benign soft tissue neoplasm of pelvis) 3
• If the nodule is determined to be reactive lymphadenopathy after workup, use R59.1 (Localized enlarged lymph nodes) 3
• If malignant transformation is identified (rare but aggressive), use appropriate C-code based on histology 7