Lipomas are encapsulated benign growths of adipocytes. They commonly present in a wide age range of adulthood. On CT imaging, they characteristically appear as well-defined nonenhancing homogeneous masses. On T1- and T2-weighted MRI, they have high signal intensity, with low signal intensity of thin septa that may be present.5 A key point of surgical management is extracapsular resection to minimize the likelihood of local recurrence. Seldom is reconstruction required following resection of lipomas, as overlying skin and adjacent tissue can be preserved.
Elastofibromas are common, slow-growing benign chest wall lesions that characteristically develop deep to the scapula. They are considered “pseudotumors” as they form due to fibroblastic proliferation. They are reported in approximately 10 to 25 percent of cadavers on autopsy. They occur in the inferior subscapular region, deep to the serratus anterior, latissimus dorsi, and rhomboid muscles. Ten percent occur bilaterally.70
Although most elastofibromas are asymptomatic, symptomatic patients present with shoulder discomfort or pain. On CT imaging, they appear as poorly circumscribed soft-tissue masses with signal intensity similar to muscle. On T1- and T2-weighted MRI, they have low signal intensity, with intervening high signal fat strands. On PET-CT, elastofibromas have increased metabolic activity with FDG uptake, which may lead to misdiagnosis of malignancy. Core-needle biopsy may be diagnostic.70
Treatment of symptomatic lesions is excision, and radiologic and tissue diagnosis should be confirmed prior to radical resection for misdiagnosis of malignancy.
Other Benign Soft-Tissue Tumors
Other benign soft-tissue tumors have been described as involving the chest wall. These are usually reported as solitary cases. Included among these are chondroid syringoma, a benign, slow-growing tumor of the eccrine and apocrine glands, with mixed epithelial and mesenchymal elements. Although these more commonly arise from salivary glands, they may occur in the axilla. These usually present as slow-growing, painless nodules of the head and neck, most commonly seen in middle-aged or older men. Rarely, these may undergo malignant transformation or metastasis.71
Diagnosis of these rare tumors presents a challenge, and is often made after surgical biopsy or resection. Treatment is margin-negative excision, and wide local resection if suspicion exists for malignancy and for tumors larger than 3 cm. Regional lymph nodes should be sampled if they are clinically palpable or suspicious.
Sarcomas of the chest wall are rare. Presentation is typically due to development of a nonpainful mass, and less frequently a painful mass, pain alone, or as an incidental finding on radiographic imaging.37 In addition to infiltration of adjacent structures, symptoms may be due to local compression and present as limb paresthesias, range of motion defects, and distal swelling of a compromised upper extremity.72 Diagnosis is made by core-needle biopsy or open biopsy. For superficial lesions less than 5 cm in diameter, excisional biopsy is used. Contrast enhanced MRI is our preferred method of evaluation of extent of the tumor (Fig. 18-24). In addition, CT of the chest should be obtained during workup for staging to rule out pulmonary metastases and regional and mediastinal lymphadenopathy. In cases of the latter, either mediastenoscopic lymph node sampling or PET scan is useful for lymph node staging.
Representative image from MRI scan of the chest of patient with recurrent sarcoma of the chest wall. The arrows mark the site of chest wall recurrence. (Image courtesy Merhan Habibi, MD.)
The goal for surgical extirpation of soft-tissue sarcomas is en bloc full-thickness chest wall resection with a 1-cm margin of normal tissue to achieve tumor-free (R0) margins. On definitive resection, the biopsy tract, including overlying skin incision site, should be excised with the specimen. The achievement of a 1-cm tumor margin may pose a technical challenge, based on anatomic relation of the tumor to adjacent structures. Grossly, tumor-positive (R2) margins necessitate reresection. When technically feasible, reresection should be performed for microscopically positive (R1) margins. Regional lymph nodes should be examined for metastases, as this may affect postoperative treatment and prognosis.
Neoadjuvant radiation therapy (50 Gy) can be used to diminish burden of disease with large tumors and improve the ability to obtain tumor-free margins for tumors involving vital structures (nerves and blood vessels). Intraoperative radiation therapy and brachytherapy may be considered for some situations, highlighting the utility of multidisciplinary management of soft-tissue sarcomas from early on in patient management.
Radiation therapy (50–60 Gy) is added postoperatively for residual disease, tumor margins less than 1 cm, tumors larger than 5 cm, or highly invasive tumors.73,74 In the instance of intracompartmental tumors treated via compartmental resection, radiation therapy is not strictly indicated.
No consensus has been reached on the utility of chemotherapy for the primary treatment of soft-tissue sarcomas. Chemotherapy is used for recurrent disease and for metastatic disease. Intraoperative brachytherapy is used selectively to sterilize deep close margins.
Local recurrence of soft-tissue sarcomas occurs in up to two-thirds of patients, and should be treated with reresection when possible, and radiation therapy should be considered.37,75 In a large series of chest wall soft-tissue sarcomas, approximately 7 percent of patients presented with synchronous metastases, and ultimately 35 percent experienced metastases.37 Lung metastases from sarcomas should be treated with chemotherapy, especially in the setting of synchronous lesions in the absence of extrapulmonary disease.73 However, isolated pulmonary lesions can be treated with wedge resection. In select populations, the latter confers up to 20 percent 5-year survival.76
Rapidity of disease recurrence is a function of malignancy grade and response to, and completeness of, definitive therapy. Recurrence is seen within 2 to 3 years in high-risk patients. To achieve early detection of local or pulmonary recurrence, we advocate regular follow-up visits with CT of the chest at 4-month intervals for the first 2 to 3 years after treatment, then every 6 months up to 5 years, and yearly thereafter.
Overall 5-year survival of chest wall soft-tissue sarcomas is 66 percent, with significantly poorer 5-year survival for those with high-grade sarcomas (49 percent) as compared with those with low-grade sarcomas (90 percent).37 In a series of patients treated with chest wall resection for high-grade sarcomas, either primary, metastatic, or recurrent, 5-year disease-free survival was 40 percent and overall 5-year survival was 59 percent, suggesting that aggressive surgical resection to establish tumor-free margins should be performed for chest wall sarcomas.50 Another study reported similar results with a 50 percent 5-year survival following chest wall resection for recurrent sarcomas.32
Desmoid tumors involving the chest wall account for between 20 and 50 percent of low-grade chest wall sarcomas.2,3,37,77–81 Desmoid tumors, also known as fibromatosis, are fibroblastic and myofibroblastic neoplasms. These histologically benign tumors arise from the connective tissue of the muscular aponeurosis, and are locally aggressive, invading adjacent structures, but usually confined to musculature and fascia. Although they most commonly occur in the abdomen, the retroperitoneum, and the extremities, approximately 20 percent of desmoid tumors occur in the chest wall and intrathoracically.82,83 On histologic examination, desmoid tumors have characteristic spindle cells separated by thick bands of collagen. These are associated with beta-catenin, adenomatous polyposis coli germline, or somatic mutations.82 They more frequently occur in females, patients with familial adenomatous polyposis, and at sites of prior trauma or scaring, such as rib fractures.81 They characteristically present as an enlarging mass, which becomes painful due to compression and invasion of local structures, including the lungs.84
Radiologic appearance varies and is based on collagen content of the tumor, and may be infiltrative or nodular in nature. Desmoid tumors are best characterized by T1-weighted MRI, where they have a signal intensity less than or comparable to muscle, and T2-weighted MRI, which can elucidate soft-tissue infiltration (Figs. 18-25 and 18-26).35 However, desmoid tumors may not be well characterized on CT imaging (Fig. 18-27). In addition, open biopsy may not yield a correct diagnosis.
T1-weighted MRI of left chest wall desmoid tumor in a 20-year-old woman. (Image courtesy of Douglas Wood, MD.)
T2-weighted MRI of left chest wall desmoid tumor in a 20-year-old woman. (Image courtesy of Douglas Wood, MD.)
Chest CT of the same patient in Figures 18-25 and 18-26 one year after initial resection of chest wall desmoid tumor and medial head of left clavicle, and subsequent reconstruction. Recurrence of the desmoid tumor is evident, as is hardware from initial reconstruction. (Image courtesy of Douglas Wood, MD.)
Treatment is radical resection with microscopically negative margins (R0) of 2 to 4 cm.82,85 The inability to achieve microscopically negative tissue margins may result in the need for radiation, which may be given pre- or postoperatively, or in lieu of surgery due to the inability to resect lesions based on anatomic constraints. Chemotherapy, anti-inflammatory therapy, and hormone therapy are reserved for situations where surgical resection is not an option, such as widespread tumor infiltration. No single agent or combination chemotherapy has been identified that elicits a response in all patients. Agents noted to induce a partial or complete response in patients include doxorubicin and dacarbazine, interferon-alpha with or without tretinoin, vinorelbine or vinblastine and methotrexate, and tamoxifen.82,86
Although between one-quarter and one-half of desmoid tumors recur locally following resection, they do not metastasize. Recurrence is associated with degree of resection. In a series of 53 patients who underwent surgery for chest wall desmoid tumors, 89 percent recurrence rate was reported in patients with micro- or macroscopically positive resection margins. Fifty percent of patients who underwent reresection developed local recurrence, as opposed to only 8 percent of those who underwent margin-negative primary resection. The 5-year local recurrence rate is between 29 and 37.5 percent, with 5-year survival of 93 percent.87,88 Lifelong follow-up with imaging and biopsy of suspicious lesions is necessary to rule out recurrence and malignancy.
Proximal-Type Epithelioid Sarcoma
Although proximal-type epithelioid sarcoma, an undifferentiated soft-tissue sarcoma, characteristically occurs in the extremities, attached to tendon, tendon sheaths, or fascia, they may occur in the chest wall.89 These present as a subcutaneous or deep dermal mass. Proximal epithelioid sarcomas, occurring in the trunk and thighs, are more aggressive than those occurring in the distal extremities. Histologically, they resemble poorly differentiated carcinoma with sheets of large cells with characteristic prominent nucleoli, and frequently have a rhabdoid phenotype.
On CT imaging, approximately one-third of these tumors have stippled calcification. On T1-weighted MRI, proximal-type epithelioid sarcomas have signal intensity equal to muscle. On T2-weighted MRI, they appear as heterogeneous masses with high signal intensity. They are intravenous contrast enhancing.35 Immunohistochemistry is necessary to differentiate proximal-type epithelioid sarcoma from other epithelioid lesions.
Treatment is wide local excision. Chemotherapy and radiation therapy have been used pre- and postoperatively. In a series of 20 patients, with mean follow-up of 4 years and 5 months, there was a 65 percent local recurrence rate, and a mean disease-free survival of 10 months. The same authors report a 75-percent rate of metastases, with metastases to lymph nodes, the lung, bone, and skin.89 Larger tumor size at presentation was correlated with poorer prognosis but not occurrence of metastasis.
Radiation-induced sarcoma of the chest wall is an aggressive tumor, occurring in patients who have undergone radiation therapy for, and survived, breast cancer and lymphoma. Tumor types described include chondrosarcomas, osteosarcomas, fibrosarcomas, malignant fibrous histiocytomas (MFHs), malignant schwannomas, and undifferentiated sarcomas. In a series of 15 patients, interval between radiation therapy and occurrence of radiation-induced sarcoma ranged between 6 and 27 years, with a median of 14 years.90 Treatment entails aggressive wide local en bloc resection, including involved skin and soft tissue, previously irradiated tissue and surgical sites, with an R1 margin of 4 cm. Rib margins include the unaffected rib above and below the tumor, and involved viscera including lung and mediastinal structures are resected. High-grade tumors are treated with adjuvant chemotherapy. Median survival of surgically managed radiation-induced sarcoma is approximately 5 years.90
Malignant Fibrous Histiocytoma
Extrapleural MFH tumors are rare tumors of mesenchymal origin, accounting for 0.6 percent of soft-tissue tumors, and between 7 and 27 percent of malignant chest wall tumors in several large series.3,37,91 They typically originate in skeletal muscle and fascia. MFH tumors develop malignant features in approximately 50 percent of cases.13 Although they predominantly occur in the pleura, extrapleural locations include chest wall, head and neck, endocrine glands, intraperitoneally, and in the retroperitoneum. Extrapleural solitary MFH tumors have a higher rate of locoregional recurrence, as well as the possibility of metastasis. When occurring in the chest wall, they are more commonly located presternally.37 Of the chest wall soft-tissue sarcomas, MFH are the least likely to metastasize, occurring in only 18 percent in one large series.37
On CT imaging, MFH appear as a heterogeneously enhancing mass in muscle or fascial planes (Fig. 18-28). The myxoid type of MFH has a characteristic appearance of central low attenuation of the myxoid matrix surrounded by enhancing nodular tissue on CT. Appearance on MRI may be variable, but on T1-weighted MRI, most MFH tumors have an appearance similar to muscle, while on T2-weighted MRI, they have the signal intensity equal or greater to that of adipose tissue.35
Representative image from CT scan of the chest of 62-year-old man with an 8.5 × 4.1 cm malignant fibrous histiocytoma encompassing the left seventh through ninth ribs prior to resection. Following resection, reconstruction of the chest wall was achieved with 2 mm Gore Tex. (Image courtesy of Michael S. Mulligan, MD.)
As with other rare sarcomas, diagnosis of MFH should be confirmed by a pathologist experienced in soft-tissue tumors and well-established pathologic criteria of malignancy exist. Treatment is resection with negative margins, with adjuvant chemotherapy and radiation therapy for malignant disease, or for margin-positive disease where additional surgical resection is not an option. Extended long-term follow-up is warranted.
Liposarcoma constitutes 15 to 20 percent of adult chest wall sarcomas, and less than 10 percent of malignant chest wall tumors.3,37 Three distinct clinicopathologic subtypes of liposarcoma exist: pleomorphic, myxoid, and well-differentiated or dedifferentiated liposarcoma. The latter is the most common subtype, accounting for 40 to 45 percent. Ten percent of liposarcomas present in the chest wall.32 A recent series of 12 dedifferentiated liposarcomas reported one involving the chest wall, the majority occurring in the retroperitoneum.92 On radiologic imaging, the different subtypes differ in appearance due to their histopathology. In general, as liposarcomas contain fat and soft tissue, they appear slightly more dense than fat on CT.35 Treatment and outcomes are comparable with that of other soft-tissue sarcomas of the chest wall, which is already discussed.
For other, rare soft-tissue malignancies, diagnosis should be confirmed by a pathologist experienced in soft-tissue tumors, as well-established pathologic criteria of malignancy exist for many tumors. These include spindle cell sarcomas, tenosynovial sarcomas, hemangiopericytomas, alveolar soft-part sarcomas, dermatofibrosarcoma protuberans, and giant cell sarcomas, each of which constitute less than 3 percent of chest wall soft-tissue sarcomas in a large series.37
Skin cancer may occur on the chest wall, with melanoma occurring particularly in areas of high sun exposure. Treatment is beyond the scope of this chapter and is discussed in-depth in other forums.