Splenius Capitis Tumors

Tumors of the splenius capitis muscle are abnormal growths—either benign or malignant—arising within or adjacent to this deep neck muscle. They fall under the umbrella of soft tissue tumors, which include a wide array of neoplastic lesions originating from muscle, fat, fibrous tissue, blood vessels, or nerve sheaths. While most splenius capitis masses are rare, understanding their nature is crucial for timely diagnosis and management PubMedPubMed Central.

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Anatomy of the Splenius Capitis Muscle

1. Structure & Location
   The splenius capitis is a broad, strap‑like muscle on the back of the neck. It lies deep to the trapezius and superficial to the semispinalis capitis and longissimus capitis, forming part of the floor of the posterior neck triangle Wikipedia.

2. Origin

   • Lower half of nuchal ligament

   • Spinous processes of C7–T3 vertebrae WikipediaPhysiopedia.

3. Insertion

   • Mastoid process of the temporal bone

   • Lateral third of the superior nuchal line of the occipital bone WikipediaPhysiopedia.

4. Blood Supply
   Muscular branches of the occipital artery (branch of the external carotid artery) Wikipedia.

5. Nerve Supply
   Posterior (dorsal) rami of spinal nerves C3 and C4 WikipediaPhysiopedia.

6. Functions

   • Bilateral contraction: head and neck extension

   • Unilateral contraction: lateral flexion of head to same side

   • Unilateral contraction: rotation of head to same side

   • Stabilization of the cervical spine in erect posture

   • Assists in head-shaking movements

   • Supports fine adjustments during jaw opening and protrusion Physiopedia.

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Types of Splenius Capitis Tumors

Splenius capitis tumors mirror the broad classification of soft tissue tumors:

1. Benign Tumors

   • Lipoma (fat cell tumor)

   • Fibroma (fibrous tissue)

   • Rhabdomyoma (skeletal muscle)

   • Hemangioma (blood vessel)

   • Schwannoma (nerve sheath)

   • Neurofibroma (nerve sheath)

   • Desmoid (deep fibromatosis) Medscapeschaberg.faculty.ucdavis.edu.

2. Intermediate (Locally Aggressive) Tumors

   • Desmoid tumors (aggressive fibromatosis)

   • Glomus tumors

   • Tenosynovial giant cell tumors ﹙nodular tenosynovitis﹚ Cancer ResourcesMedscape.

3. Malignant Tumors (Soft Tissue Sarcomas)

   • Rhabdomyosarcoma (embryonal, alveolar, pleomorphic)

   • Leiomyosarcoma (smooth muscle)

   • Liposarcoma (well‑differentiated, dedifferentiated, myxoid, pleomorphic)

   • Fibrosarcoma

   • Malignant peripheral nerve sheath tumor (MPNST)

   • Angiosarcoma (vascular)

   • Synovial sarcoma

   • Undifferentiated pleomorphic sarcoma PubMed CentralMedscape.

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Causes of Splenius Capitis Tumors

Many factors can predispose to tumor formation in skeletal muscle. Key causes include:

1. Radiation Exposure (therapeutic) Cancer Resources

2. Inherited Cancer Syndromes

   • Neurofibromatosis type 1 (NF1) Cancer Resources

   • Gardner syndrome (APC gene defect) Cancer Resources

   • Li‑Fraumeni syndrome (TP53 mutation) Cancer Resources

   • Retinoblastoma (RB1 mutation) Cancer Resources

   • Werner syndrome (RECQL2 mutation) Cancer Resources

   • Gorlin syndrome (PTCH1 mutation) Cancer Resources

   • Tuberous sclerosis (TSC1/TSC2 mutation) Cancer Resources

3. Chronic Lymphedema (Stewart–Treves syndrome) Cancer Resources

4. Chemical Exposures

   • Vinyl chloride Cancer Resources

   • Arsenic Cancer Resources

   • Dioxin Cancer Resources

   • Phenoxyacetic acid herbicides Cancer Resources

5. Spontaneous DNA Mutations (acquired) Cancer Resources

6. Oncogene Activation & Tumor Suppressor Inactivation Cancer Resources

7. Viral Oncogenesis

   • HHV‑8 causing Kaposi sarcoma Cancer Resources

   • EBV‑associated smooth muscle tumors

8. Immunosuppression (e.g., HIV, post‑transplant)

9. Occupational Toxins (aromatic amines, chlorophenols)

10. Malignant Transformation of Benign Lesions (e.g., neurofibroma → MPNST)

11. Chronic Inflammation & Injury (controversial)

12. Age (higher risk in older adults)

13. Gender Differences (slightly higher in males)

14. Genetic Instability (microsatellite instability)

15. Epigenetic Alterations (DNA methylation changes)

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Symptoms of Splenius Capitis Tumors

Splenius capitis tumors may present with both local and systemic signs:

1. Noticeable lump or mass in the back of the neck

2. Pain or tenderness over the muscle Cancer Resources

3. Stiffness and reduced neck range of motion

4. Difficulty turning or tilting the head

5. Muscle spasms in the neck

6. Local swelling and fullness

7. Sensation of tightness or pressure

8. Radiating pain into shoulders or upper back

9. Paresthesia (numbness/tingling) in neck or arm

10. Weakness of neck muscles

11. Head tilt (torticollis)

12. Visible or palpable pulsations (if vascular)

13. Skin changes overlying tumor (redness, warmth)

14. Ulceration or breakdown of skin (rare)

15. Visible deformity of the neck contour

16. Swollen regional lymph nodes

17. Systemic weight loss

18. Fever or night sweats

19. Fatigue and malaise

20. Neurological symptoms (if nerve compression)

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Diagnostic Tests

Evaluation of a suspected splenius capitis tumor includes:

1. Detailed medical history & physical exam

2. Palpation of mass characteristics (size, mobility)

3. Ultrasound (characterize solid vs cystic)

4. Magnetic Resonance Imaging (MRI) (soft tissue detail)

5. Computed Tomography (CT) (bone involvement)

6. X‑ray (calcifications, bone changes)

7. Positron Emission Tomography (PET‑CT) (metastatic spread)

8. Bone Scan (skeletal metastases)

9. Angiography (vascular tumors)

10. Electromyography (EMG) (distinguish neuropathy vs tumor)

11. Core Needle Biopsy (histology)

12. Fine Needle Aspiration (cytology)

13. Excisional Biopsy (small tumors)

14. Histopathology with Immunohistochemistry

15. Flow Cytometry (lymphoid markers)

16. Cytogenetic Analysis (translocations)

17. Molecular Testing (fusion genes, e.g., SYT‑SSX)

18. Tumor Markers (rarely specific)

19. Complete Blood Count (CBC), ESR, CRP (inflammatory markers)

20. Chest Imaging (rule out lung metastases)

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Non‑Pharmacological Treatments

Supportive and adjunctive therapies include:

1. Physical therapy (stretching, strengthening)

2. Heat therapy (moist heat packs)

3. Cold therapy (ice packs)

4. Massage therapy (manual muscle relaxation)

5. Posture correction exercises

6. Ergonomic workstation adjustments

7. Acupuncture

8. Dry needling

9. Transcutaneous Electrical Nerve Stimulation (TENS)

10. Therapeutic ultrasound

11. Low‑level laser therapy

12. Yoga for neck flexibility

13. Pilates for core strengthening

14. McKenzie neck exercises

15. Cervical traction therapy

16. Biofeedback

17. Kinesio taping

18. Assistive cervical collars (soft)

19. Aquatic therapy

20. Hydrotherapy

21. Nutritional support (anti‑inflammatory diet)

22. Mindfulness meditation

23. Relaxation techniques

24. Cognitive‑behavioral therapy

25. Lymphatic drainage massage (for lymphedema)

26. Chiropractic adjustments (with caution)

27. Osteopathic manipulation

28. Ergonomic pillows/mattresses

29. Post‑surgical scar mobilization

30. Patient education and support groups

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Drugs Used

Analgesics & Symptomatic Relief

1. Acetaminophen

2. Ibuprofen

3. Naproxen

4. Diclofenac

5. Celecoxib

6. Morphine

7. Oxycodone

8. Gabapentin

9. Pregabalin

10. Cyclobenzaprine (muscle relaxant)

11. Prednisone (corticosteroid)

Chemotherapy & Targeted Agents

12. Doxorubicin

13. Ifosfamide

14. Gemcitabine

15. Docetaxel

16. Dacarbazine

17. Trabectedin

18. Eribulin

19. Pazopanib (TKI)

20. Temozolomide

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Surgical Procedures

1. Excisional Biopsy (small, accessible tumors)

2. Wide Local Excision (margin clearance)

3. Marginal Excision (closer margins, when wide excision risks function)

4. Radical En Bloc Resection (including adjacent structures)

5. Debulking Surgery (reduce tumor bulk before adjuvant therapy)

6. Sentinel Lymph Node Biopsy (staging)

7. Nerve‑Sparing Resection (protect neurovascular bundles)

8. Reconstructive Flap Surgery (e.g., trapezius, latissimus dorsi flap)

9. Cervical Spine Stabilization (if vertebral involvement)

10. Radical Neck Dissection (if nodal metastases)

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Prevention Strategies

1. Minimize therapeutic radiation when possible

2. Genetic counseling & testing for high‑risk syndromes

3. Protective measures against chemical exposures

4. Prompt treatment of chronic lymphedema

5. Safe‑sex practices to reduce HHV‑8 transmission Cancer Resources

6. Occupational safety protocols (masks, gloves)

7. Regular surveillance in NF1 or Li‑Fraumeni patients

8. Healthy lifestyle (balanced diet, regular exercise)

9. Avoidance of known carcinogens (arsenic, dioxin)

10. Early evaluation of persistent neck lumps

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When to See a Doctor

• A new neck lump that persists or grows over weeks

• Painful or tender mass in the back of the neck

• Restricted neck movement or torticollis

• Neurological signs (numbness, weakness in arm)

• Skin changes (redness, ulceration)

• Systemic symptoms (unexplained weight loss, night sweats, fever)

• Any deep mass > 5 cm in diameter Cancer Resources

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Frequently Asked Questions

1. What is a splenius capitis tumor?
   A growth arising in the splenius capitis muscle, which may be benign or malignant.

2. How common are these tumors?
   Extremely rare; only a small fraction of soft tissue tumors occur in the splenius capitis.

3. Are they painful?
   Some are painful (especially malignant or inflamed), while others (like lipomas) are often painless.

4. How are they diagnosed?
   Through imaging (MRI/CT), biopsy, and histopathology.

5. Can they become cancerous?
   Benign tumors rarely transform; malignant tumors (sarcomas) are inherently cancerous.

6. What treatments are available?
   Surgery with clear margins, possibly combined with chemotherapy or radiation.

7. Is surgery risky?
   Risks include nerve injury, bleeding, and reduced neck mobility.

8. What is the prognosis?
   Benign tumors have excellent outcomes; prognosis for sarcomas depends on size, grade, and margins.

9. Can physical therapy help?
   Yes—post‑surgery rehab is crucial for restoring function.

10. Do these tumors recur?
    Malignant tumors have higher recurrence rates; complete excision reduces risk.

11. Are there support groups?
    Yes—many sarcoma-specific patient advocacy groups exist.

12. Can genetics play a role?
    Yes—certain inherited syndromes (e.g., Li‑Fraumeni) increase risk.

13. Is radiation therapy used?
    It may be employed after surgery or for unresectable tumors.

14. What if I have a neck injury?
    Injury itself doesn’t cause tumors, but it may make an existing tumor more noticeable Cancer Resources.

15. How can I reduce my risk?
    Avoid known risk factors and seek early evaluation for persistent lumps.

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The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members

Last Update: April 16, 2025.

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