Residency · Residency · Plastic Surgery

Melanoma and Soft Tissue Tumor Reconstruction

Introduction

Melanoma is the most aggressive skin cancer, accounting for the majority of skin cancer deaths despite representing only 4% of skin cancer diagnoses. Soft tissue sarcomas are rare mesenchymal malignancies arising from fat, muscle, nerve, and connective tissue; require multidisciplinary oncologic management. The plastic surgeon plays a dual role: ensuring adequate oncologic resection and providing optimal wound reconstruction. Reconstruction must balance achieving a durable, functional wound closure with facilitating oncologic surveillance and potential adjuvant therapy. Understanding of tumor biology, staging, and margin requirements is essential for surgical planning.

Melanoma

Epidemiology and Risk Factors

Incidence: approximately 100,000 new cases annually in the United States; rising incidence worldwide. Risk factors: UV exposure (intermittent intense exposure), fair skin (Fitzpatrick I-II), >50 nevi, dysplastic nevi, family history, immunosuppression, CDKN2A mutations. ABCDE criteria for suspicious lesions: Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolving.

Pathology and Staging

Breslow thickness: measured from granular layer to deepest point of invasion; most important prognostic factor. Clark level: depth of anatomic invasion (I-V); less prognostically significant than Breslow depth. Ulceration: independent adverse prognostic factor; upstages the T classification. Mitotic rate: high mitotic index (>1/mm²) associated with worse prognosis.

Sentinel lymph node biopsy (SLNB): indicated for melanomas >0.8 mm thickness or thinner melanomas with adverse features (ulceration, high mitotic rate). AJCC 8th edition staging: T classification based on thickness and ulceration; N classification based on number of involved nodes and presence of in-transit/satellite metastases.

Surgical Margins

Margins extend to but do not include the deep fascia unless clinically involved. On the face, ears, and digits, margins may need modification; Mohs micrographic surgery or staged excision with complete circumferential margin assessment is preferred.

Sentinel Lymph Node Biopsy

Lymphoscintigraphy: preoperative injection of radiotracer (Tc-99m sulfur colloid) and/or blue dye (isosulfan blue, methylene blue) to identify the sentinel node. SLNB identifies microscopic nodal metastasis; positive SLNB is the strongest predictor of melanoma-specific survival. Completion lymph node dissection (CLND): historically performed for positive SLNB; MSLT-II and DeCOG-SLT trials demonstrated no survival benefit for CLND; nodal observation with ultrasound surveillance is now standard. SLNB is a staging procedure; it provides prognostic information and identifies candidates for adjuvant systemic therapy (immunotherapy, targeted therapy).

<image>Diagram illustrating melanoma staging and surgical management: cross-sectional view of skin showing Breslow thickness measurements corresponding to T1-T4 classifications, recommended excision margins for each stage, and the sentinel lymph node biopsy technique with radiotracer and blue dye injection</image>

Soft Tissue Sarcomas

Classification and Staging

Over 70 histologic subtypes: liposarcoma, undifferentiated pleomorphic sarcoma (formerly MFH), leiomyosarcoma, synovial sarcoma, fibrosarcoma, dermatofibrosarcoma protuberans (DFSP). Most common in the extremities (60%), retroperitoneum (20%), trunk (10%), head and neck (10%). Grading (FNCLCC system): based on differentiation, mitotic count, and necrosis; grade is the strongest predictor of metastasis. Staging: AJCC system incorporates tumor size, depth (superficial vs. deep to fascia), grade, and nodal/distant metastasis.

Surgical Principles for Sarcoma

Wide local excision with negative margins (1-2 cm or fascial margin) is the standard. Limb-sparing surgery + radiation is equivalent to amputation for extremity sarcomas in survival outcomes (NCI trial, Rosenberg 1982). R0 resection (microscopically negative margins) is the goal; R1 (microscopic positive) margins increase local recurrence; R2 (gross residual) disease requires re-excision. Critical structures (major vessels, nerves, bone) adjacent to tumor may require reconstruction after en bloc resection.

Special Consideration: DFSP

Dermatofibrosarcoma protuberans: low-grade sarcoma of the dermis/subcutis with tentacle-like extensions. High local recurrence rate with standard excision; Mohs micrographic surgery reduces recurrence to <1%. Wide excision margins of 2-3 cm if Mohs is unavailable. Metastasis is rare (<5%); fibrosarcomatous transformation increases metastatic risk.

Reconstruction After Oncologic Resection

Principles

Reconstruction should not compromise oncologic outcome: ensure negative margins before definitive closure; consider frozen section or staged reconstruction. Facilitate surveillance: avoid excessively bulky reconstruction that obscures the tumor bed; plan for clinical and imaging follow-up. Accommodate adjuvant therapy: radiation ports should not be obstructed; reconstruction must tolerate radiation (vascularized tissue preferred over grafts in irradiated fields). Functional preservation: maintain limb function, joint mobility, and sensory innervation when possible.

Reconstructive Options by Anatomic Site

Head and Neck

Facial melanoma with wide margins often creates significant functional and aesthetic defects. Local flaps (cervicofacial advancement, bilobed, paramedian forehead) for moderate defects. Free tissue transfer (RFFF, ALT) for large composite defects involving bone or through-and-through defects. Parotidectomy defects: SCM flap or free flap to fill the defect and prevent Frey syndrome.

Trunk

Wide excision of trunk melanoma or sarcoma may expose bone, hardware, or viscera. Primary closure or skin grafts for superficial defects. Local muscle flaps (latissimus dorsi, pectoralis, rectus abdominis) for deep defects. Free flaps for large defects or irradiated fields where local options are insufficient.

Extremities

Sarcoma resection in the extremities frequently exposes bone, tendon, vessels, or nerves. Gastrocnemius flap (proximal tibia), soleus flap (middle tibia): workhorse options for leg defects. ALT free flap, gracilis free flap, latissimus dorsi free flap: for large extremity defects. Vascular reconstruction: if major vessels are resected en bloc, interposition vein grafts or prosthetic grafts may be required.

Functional muscle transfer: when motor units are sacrificed, free functional muscle transfer (gracilis) may restore function.

<image>Reconstructive algorithm flowchart for soft tissue defects after oncologic resection organized by size and depth: superficial defects managed with skin grafts or local flaps, intermediate defects with regional muscle flaps, and complex defects with free tissue transfer, with decision points for radiation and functional requirements</image>

Adjuvant Therapy Considerations

Radiation Therapy

Sarcoma: adjuvant radiation (50-66 Gy) reduces local recurrence from 30% to <10% for intermediate/high-grade tumors. Melanoma: adjuvant radiation for desmoplastic melanoma, positive margins, or extensive nodal disease. Radiation affects reconstruction: increased risk of wound complications, flap contracture, fat necrosis, and implant complications. Vascularized tissue (flaps) tolerates radiation better than skin grafts or primary closure under tension.

Systemic Therapy

Melanoma: checkpoint inhibitors (nivolumab, pembrolizumab) and targeted therapy (BRAF/MEK inhibitors for BRAF-mutant melanoma) have revolutionized adjuvant and metastatic treatment. Sarcoma: neoadjuvant/adjuvant chemotherapy (doxorubicin-based) for high-grade, large, deep tumors; limited survival benefit in most subtypes. Systemic therapy can affect wound healing: coordinate timing of reconstruction with medical oncology.

Complications

Wound dehiscence: higher rates in irradiated fields and after sarcoma resection due to large dead space. Seroma/hematoma: common after large resections; drain placement and compression reduce risk. Flap failure: 2-5% for free flaps; increased risk in irradiated tissue. Local recurrence: requires re-excision; reconstruction must allow access for surveillance; consider staged excision before definitive reconstruction if margins are uncertain.

Lymphedema: after lymph node dissection; affects 20-30% of patients; managed with compression, physical therapy, and potentially lymphovenous bypass.

<image>Clinical photograph series showing extremity sarcoma management: (A) MRI of a high-grade soft tissue sarcoma of the anterior thigh, (B) intraoperative photograph after wide excision with exposed femoral vessels and quadriceps resection, (C) ALT free flap from the contralateral thigh providing soft tissue coverage and obliteration of dead space</image>

Key Clinical Pearls

Melanoma excision margins are dictated by Breslow thickness; sentinel lymph node biopsy is a staging procedure indicated for tumors greater than 0.8 mm. Completion lymph node dissection is no longer standard for positive sentinel nodes; nodal observation with ultrasound surveillance is current practice (MSLT-II). For soft tissue sarcomas, limb-sparing surgery with adjuvant radiation achieves equivalent survival to amputation. Reconstruction after oncologic resection must prioritize negative margins, facilitate surveillance, and tolerate adjuvant radiation therapy. Coordinate reconstruction timing with medical oncology to avoid delays in systemic therapy; free tissue transfer is preferred in irradiated fields.

References

1. Wong SL, Faries MB, Kennedy EB, et al. Sentinel lymph node biopsy and management of regional lymph nodes in melanoma: American Society of Clinical Oncology and Society of Surgical Oncology clinical practice guideline update. J Clin Oncol. 2018;36(4):399-413.
2. Faries MB, Thompson JF, Cochran AJ, et al. Completion dissection or observation for sentinel-node metastasis in melanoma (MSLT-II). N Engl J Med. 2017;376(23):2211-2222.
3. Rosenberg SA, Tepper J, Glatstein E, et al. The treatment of soft-tissue sarcomas of the extremities: prospective randomized evaluations of limb-sparing surgery plus radiation therapy. Ann Surg. 1982;196(3):305-315.
4. Bichakjian CK, Halpern AC, Johnson TM, et al. Guidelines of care for the management of primary cutaneous melanoma. J Am Acad Dermatol. 2011;65(5):1032-1047.

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