Myoepithelial Carcinoma: Symptoms, Causes, Diagnosis, Treatment & Prognosis

Myoepithelial carcinoma is a rare and potentially aggressive malignant tumor that arises from myoepithelial cells — specialized cells found in glands such as the salivary glands, sweat glands, and breast tissue. Although uncommon, this cancer can develop in both soft tissue and visceral organs and may behave aggressively depending on its location and molecular characteristics.

Because myoepithelial carcinoma is rare, it is often misdiagnosed or confused with other soft tissue or salivary gland tumors. Early recognition and accurate histopathological diagnosis are crucial for effective treatment.

This comprehensive guide covers myoepithelial carcinoma symptoms, causes, risk factors, diagnosis, treatment options, recurrence risk, and survival rates.

~What Is Myoepithelial Carcinoma?

Myoepithelial carcinoma (also called malignant myoepithelioma) is a cancer that originates from myoepithelial cells. These cells normally surround glandular structures and help expel secretions.

It can occur in:

• Salivary glands (most common site)

• Soft tissues

• Skin

• Breast

• Lung (rare)

• Bone (rare)

When it arises in salivary glands, it is classified under salivary gland malignancies. It may develop on its own or evolve from a benign tumor such as pleomorphic adenoma.

~Common Locations of Myoepithelial Carcinoma

1. Salivary Glands (Most Common)

                                                                                                The parotid gland is the most frequently affected salivary gland. Tumors may also arise in minor salivary glands located in the palate and oral cavity.

Symptoms include:

• Painless swelling near the jaw or ear

• Facial nerve weakness (advanced cases)

• Difficulty swallowing (rare)

2. Soft Tissue Myoepithelial Carcinoma

Soft tissue forms may occur in:

• Extremities (arms and legs)

• Trunk

• Deep muscle tissue

These tumors may present as:

• Slowly enlarging mass

• Firm or rubbery lump

• Pain (if compressing nerves)

3. Skin (Cutaneous Myoepithelial Carcinoma)

Rarely, myoepithelial carcinoma can arise in the skin, often confused with other skin cancers.

~Symptoms of Myoepithelial Carcinoma

Symptoms depend on tumor location.

General Symptoms

• Growing mass

• Local pain

• Swelling

• Firm nodular lesion

Salivary Gland Symptoms

• Jaw or neck lump

• Facial asymmetry

• Numbness or facial paralysis

Soft Tissue Symptoms

• Deep tissue swelling

• Restricted movement

• Tenderness

Some tumors remain painless for months, leading to delayed diagnosis.

~Causes and Risk Factors

The exact cause of myoepithelial carcinoma is not fully understood. However, several factors may contribute.

1. Genetic Alterations

Some tumors show EWSR1 gene rearrangements. These molecular abnormalities help confirm diagnosis.

2. Malignant Transformation

In some cases, myoepithelial carcinoma develops from a benign tumor such as:

Pleomorphic adenoma

This transformation increases aggressiveness.

3. Radiation Exposure

Prior radiation therapy to the head and neck may increase risk.

4. Age

Most cases occur in adults between 30 and 60 years, but it can affect children as well.

~How Is Myoepithelial Carcinoma Diagnosed?

Due to its rarity, diagnosis requires specialized pathological evaluation.

1. Clinical Examination

A persistent mass that continues to enlarge should raise suspicion.

2. Imaging Studies

Doctors may use:

• MRI (preferred for soft tissue tumors)

• CT scan

• Ultrasound

Imaging helps assess:

• Tumor size

• Local invasion

• Lymph node involvement

3. Biopsy

A biopsy is essential for diagnosis.

Types include:

• Core needle biopsy

• Excisional biopsy

• Fine needle aspiration (salivary gland cases)

4. Histopathology

Under the microscope, myoepithelial carcinoma shows:

• Cellular atypia

• High mitotic activity

• Infiltrative growth

• Variable morphology (spindle, epithelioid, clear cell, or plasmacytoid cells)

5. Immunohistochemistry

Tumor cells often express markers such as:

• Cytokeratin

• S100 protein

• Calponin

• Smooth muscle actin (SMA)

• GFAP (occasionally)

These markers confirm myoepithelial differentiation.

~Staging of Myoepithelial Carcinoma

Staging depends on:

• Tumor size

• Local invasion

• Lymph node involvement

• Distant metastasis

Soft tissue tumors are staged using sarcoma staging systems.

Common metastatic sites include:

• Lungs

• Lymph nodes

• Bone

• Liver

~Treatment of Myoepithelial Carcinoma

Treatment depends on tumor location, size, and spread.

1. Surgical Removal (Primary Treatment)

Complete surgical excision with clear margins is the main treatment.

For salivary gland tumors:

• Parotidectomy (partial or total)

• Possible facial nerve preservation or reconstruction

For soft tissue tumors:

• Wide local excision

Clear surgical margins significantly reduce recurrence risk.

2. Radiation Therapy

Radiation may be recommended when:

• Margins are positive

• Tumor is large

• High-grade features are present

• Local recurrence occurs

3. Chemotherapy

Chemotherapy is considered in:

• Metastatic disease

• Unresectable tumors

• Recurrent aggressive cases

There is no standardized chemotherapy protocol due to rarity.

4. Targeted Therapy and Research

Molecular profiling may guide targeted therapy in advanced cases, particularly when EWSR1 rearrangement is identified.

Clinical trials are ongoing for rare sarcoma subtypes.

~Recurrence Risk

Myoepithelial carcinoma has a moderate to high recurrence rate, particularly in:

• Incomplete excision

• High-grade tumors

• Deep soft tissue locations

Recurrence may occur locally or as distant metastasis.

Long-term follow-up is essential, often for 5–10 years.

~Prognosis and Survival Rate

Prognosis depends on several factors:

Favorable Factors

• Small tumor size

• Complete surgical excision

• Low mitotic rate

Poor Prognostic Factors

• Large tumor

• High-grade histology

• Metastasis at diagnosis

• Positive margins

Overall 5-year survival rates vary widely (approximately 50–80%), depending on stage and location.

Soft tissue myoepithelial carcinomas may behave more aggressively than salivary gland tumors.

~Differential Diagnosis

Because of its varied appearance, myoepithelial carcinoma may be confused with:

• Epithelioid sarcoma

• Synovial sarcoma

• Metastatic carcinoma

• Clear cell sarcoma

• Malignant peripheral nerve sheath tumor

Accurate pathology review is crucial.

~Living With Myoepithelial Carcinoma

Patients may require multidisciplinary care involving:

• Surgical oncologist

• Radiation oncologist

• Pathologist

• Head and neck specialist (salivary tumors)

Rehabilitation may include:

• Physical therapy (extremity tumors)

• Facial nerve therapy (parotid tumors)

• Psychological support

~Follow-Up and Monitoring

Regular follow-up visits are critical.

Monitoring typically includes:

• Physical exams every 3–6 months (first 2 years)

• Imaging as needed

• Chest scans to detect lung metastasis

Early detection of recurrence improves outcomes.

~When to See a Doctor

Seek medical evaluation if you notice:

• A growing mass in the neck, jaw, or limbs

• Persistent painless swelling

• Facial nerve weakness

• Recurrent salivary gland lump

• Deep tissue mass that continues enlarging

Prompt biopsy improves early detection.

~Frequently Asked Questions

Is myoepithelial carcinoma rare?

Yes, it is a rare cancer affecting both salivary glands and soft tissue.

Is it aggressive?

It can be aggressive, especially high-grade or metastatic forms.

Can it spread?

Yes, it may metastasize to lungs, lymph nodes, or bone.

Is it curable?

Early-stage tumors treated with complete surgical excision have better outcomes.

~Key Takeaways

• Myoepithelial carcinoma is a rare malignant tumor of glandular and soft tissue origin.

• Most commonly affects salivary glands and extremities.

• Diagnosis requires biopsy and immunohistochemical testing.

• Surgery is the primary treatment.

• Recurrence and metastasis are possible.

• Long-term monitoring is essential.

~Conclusion

Myoepithelial carcinoma is a rare but potentially serious malignancy that requires prompt diagnosis and aggressive management. Its variable presentation and resemblance to other tumors make expert pathological evaluation essential.

Complete surgical removal remains the cornerstone of treatment, often combined with radiation therapy in high-risk cases. Due to the possibility of recurrence and metastasis, long-term follow-up is critical.

Awareness of symptoms and early medical evaluation can significantly improve prognosis and survival outcomes.