British Journal of Radiology (2007) 80, e44-e47
© 2007 British Institute of Radiology
doi: 10.1259/bjr/30984808
A giant malignant peripheral nerve sheath tumour of the breast: CT and pathological findings
O H Woo, MD
1
H S Yong, MD
1
J B Lee, MD
2
A Kim, MD
3
B H Koo, MD
2 and
E-Y Kang, MD
1
Departments of 1 Radiology, 2 Surgery and 3 Pathology, College of Medicine, Korea University, Korea University Guro Hospital, 97 Guro-dong, Guro-ku, Seoul, 152-703, Korea
Correspondence: Eun-Young Kang, Department of Radiology, Korea University Guro Hospital, 97 Guro-dong, Guro-ku, 152-703, Seoul, Korea. E-mail: keyrad{at}korea.ac.kr
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Abstract
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Malignant peripheral nerve sheath tumour (MPNST) is a rare soft tissue sarcoma. In particular, primary MPNST of the breast is extremely rare. We report a case of a giant malignant peripheral nerve sheath tumour involving the entire right breast, which was not associated with neurofibromatosis type 1 (NF-1) or previous radiation therapy. A CT scan showed a huge heterogeneous soft tissue mass with well-enhanced nodules at its periphery and low-density internal necrosis, which was confirmed by modified radical mastectomy.
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Introduction
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Most primary tumours of the breast have an epithelial origin, and non-epithelial tumours arising from indigenous structures in the breast are rare [1]. Malignant peripheral nerve sheath tumour (MPNST) is a rare sarcomatous tumour of unknown aetiology [2], which can arise in any anatomical site, but a primary mammary localization is exceptional. A review of the English literature yielded six cases of mammary MPNST [3, 4]. To our knowledge, the radiological appearance of primary MPNST of the breast has not been described in previous literature. In this case report, we present the CT and pathological findings of massive MPNST in a 56-year-old woman, which involved the entire right breast, and which was not associated with neurofibromatosis type 1 (NF-1) or previous radiation therapy.
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Case report
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A 56-year-old woman presented with a huge mass in the right breast. She had first noticed the mass some 10 years previously. It had grown substantially over this period and had gradually become necrotic. She had no other past medical history of note, no family history of breast, colon, or ovarian cancer, and was not on any medication. During physical examination, the mass was found to involve the entire right breast. The central to medial portion of the right breast, including the nipple, had rotted due to severe necrosis, and a substantial portion of the mass was exposed outside the skin (Figure 1a
). The tumour tissue was very friable with a profuse foul-odoured discharge. Laboratory findings were normal, except for a haemoglobin level (Hb) of 6.4 g dl–1. Tumour markers were normal, including CEA, CA125, and CA15-3.
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Figure 1. A 56-year-old woman with malignant peripheral nerve sheath tumour of breast. (a) Gross findings of the tumour. The tumour involved the entire right breast, which suffered extensive necrosis and inflammation. (b) Axial CT image shows a heterogeneous soft tissue mass with multiple well-enhanced nodules at its periphery and extensive internal necrosis. (c) Sagittal reconstruction CT image shows the huge breast mass, which protruded beyond the skin, involving the pectoralis and intercostal muscles. (d) The photograph of the mastectomy gross specimen shows the necrotizing, heterogeneous, haemorrhagic, solid nature of the mass and of tumour with a flesh, myxoid and white-tan appearance in the mass periphery. (e) Photomicrograph of a histopathological specimen shows intersecting fascicles of spindle cells and the cellular fascicles alternated with hypocellular areas (haematoxylin and eosin (H&E) x40). Inset image shows dense cellularity and mitoses in high power section (H&E staining x200).
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Chest CT scan was performed using a 16 channel multi-detector CT (Somatom Sensation 16; Siemens Medical systems, Erlangen, Germany) using 110 mAs, 120 kVp and 1.5 mm collimation. CT scans showed a heterogeneous soft tissue mass, measuring 29x23x24 cm. Multiple and well-enhanced nodules were observed in the mass periphery and low-density necrosis within (Figure 1b
). Skin necrosis was observed in the medial portion of the mass, which protruded out of the skin. The tumour involved the pectoralis and intercostal muscles (Figure 1c), but rib destruction was not visible. There was no definite invasion into the intrathoracic region, but pleural effusion was observed in the right hemithorax. The pleural fluid examination was negative for malignancy and no abnormal lesion was observed in either lung. There were no findings of lymphadenopathy in the axilla or internal mammary lymph node. Abdominal CT scan, brain MRI and bone scan showed no evidence of metastasis.
Staphylococcus aureus was identified by bacterial culture of the discharge from the necrotic tumour. Although there were no symptoms or signs of generalized infection, systemic antibiotics were administered for several days before surgery to allay disseminating inflammation. An incisional biopsy of the mass was performed. Along with the extensive necrosis, sarcoma was suspected, but no specific type could be discerned because of the predominating necrosis. At a later date, the patient underwent a modified radical mastectomy with right axillary dissection. In the operative field, the pectoralis muscle and the third to sixth intercostal muscles were found to be involved, but ribs were intact and no extension into the thoracic cage was evident. Because primary skin closure was impossible, the defect in the right anterior chest wall was reconstructed using a pedicled latissimus dorsi muscle flap and a split thickness skin graft from the right thigh.
The gross specimen showed that breast tissue had been replaced by a 30x27x26 cm dark greyish mass attached to a sheath of skin containing the nipple areolar complex. On serial section, the mass contents appeared as a necrotizing heterogeneous haemorrhagic solid mass, whereas peripheral tissue had a flesh, myxoid and white-tan appearance (Figure 1d). In microscopic examinations (Figure 1e), the mass was composed of intersecting fascicles of spindle cells. The cellular fascicles alternated with hypocellular areas. An immunohistochemical panel was performed and the tumour was found positive for neurofilament, vimentin, S-100 protein and Leu7. These pathological findings were compatible with MPNST.
Café-au-lait or cutaneous nodule was not found in the face, chest, or abdominal regions at the physical examination in relevance to NF-1 after operation. During the 6 months following the TRAM flap surgery, she remained in good general health without evidence of the local or distant metastasis.
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Discussion
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Malignant peripheral nerve sheath tumour (MPNST) is a rare sarcomatous tumour, representing only 5–10% of soft tissue sarcomas. MPNST arises from a nerve or neurofibroma and demonstrates nerve tissue differentiation [2]. MPNST is the currently preferred term for this neoplasm, which has also been known over the years as malignant schwannoma, neurogenic sarcoma, malignant neurilemmoma and neurofibrosarcoma. It usually affects patients who are 20–50 years old, but develops earlier when related to NF-1 [5]. Approximately half of these tumours arise de novo, and the other half from nerves involved by neurofibromas as part of NF-1. In patients with NF-1, a sudden increase in the size of a previously stable neurofibroma should be viewed with great suspicion of malignant transformation and requires immediate biopsy. Some MPNSTs have occurred in areas of previous irradiation. According to Laskin et al [6], the irradiation of peripheral nerves causes their appearance. Such tumours develop after a long latent period (10–20 years) following irradiation and account for 11% of MPNST [2]. Histologically, the diagnosis of MPNST is often only presumptive and dependent on a combination of features, none of which is uniquely diagnostic. Spindle-shaped cells have irregular contours with curved cores and a slightly coloured cytoplasm. Cellular density and organization are variable and the palisade provision of the cores is found. On immunohistochemical staining, tumour cells show reactivity to Schwann's cell markers, such as S-100 protein and Leu7, in approximately a half of cases. If a tumour is larger than 5 cm, haemorrhagic and necrotic areas are commonly observed inside the mass [7].
MPNSTs with an intramammary or juxta-mammary localization are rare. To our knowledge only six cases have been reported in the English literature [3, 8], the majority of which were associated with NF-1 or previous radiation therapy. Thus, primary MPNST of the breast not associated with NF-1 or previous radiation therapy is exceptional. Although a case of primary MPNST of the breast was reported by Catania et al [4], the radiological findings of this entity have not been reported.
MPNSTs in the breast share imaging findings with other neurogenic tumours. By mammography, the tumour may present in the form of a well or poorly defined dense nodule with or without calcifications [4, 6]. Although CT and MRI offer little help demonstrating the malignant nature of peripheral nerve sheath tumours, certain findings should raise suspicion of a malignant tumour, i.e. a large tumour (>5 cm) with heterogeneity, ill-defined margins, invasion of fat planes and perilesional oedema would favour a diagnosis of MPNST [5, 7]. In our case, the tumour was approximately 30 cm in size and showed extensive internal necrosis by CT with well-enhanced nodules at the mass periphery. Therefore, we considered the lesion malignant. During differential diagnosis, the enormous size of the mass was evident, but lymph node metastasis was absent; thus, a sarcoma such as cystosarcoma phyllodes was first suspected. The patient had no history of specific diseases and thus MPNST was not included in the differential diagnosis of the imaging study, because primary MPNST is rare in the breast. However, well-enhanced multiple nodules in the periphery of the mass that had the typical appearance of MPNST in terms of histological aspects and extensive central necrosis on the chest CT were consistent with MPNST. CT findings, which showed extensive central necrosis and an aggressively growing tumour at the mass periphery as the mass became larger, depicted the natural evolution of this tumour.
With regard to treatment, the majority of authors seemed to agree on the role of surgery [9, 10]. The biopsy is required to diagnose primary MPNST of the breast, because imaging techniques do not usually produce characteristic findings. A pre-operative diagnosis using two percutaneous core biopsies or fine needle aspiration cytology is relatively reliable [11], but a mass with extensive necrosis such as in this case cannot be differentiated from other sarcoma or malignant tumour. Therefore, radical or modified radical mastectomy is advised for such breast lesions. Radiation therapy is often helpful in decreasing the likelihood of local recurrence [9], but may be contraindicated in the event of a radiation-induced tumour [6]. Moreover, chemotherapy proved unreliable, although in some cases it was found to limit dissemination and reduce tumoural volume pre-operatively [3]. Our patient was treated by modified radical mastectomy and axillary lymph node dissection. We can consider providing additional radiation therapy for this patient after complete wound healing to prevent local recurrence.
To our knowledge, this is the first report to include the radiological findings of primary MPNST of the breast that is not associated with NF-1 or previous radiation therapy. CT showed extensive central necrosis with peripheral well-enhanced nodules within a huge solid breast mass, but without direct intrathoracic extension or distant metastasis. Despite its rarity, we should be alert to the existence of this type of soft tissue sarcoma of the breast.
Received for publication September 12, 2005.
Revision received December 13, 2005.
Accepted for publication March 13, 2006.
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Abstract
Introduction
