British Journal of Radiology (2009) 82, e1-e2
© 2009 British Institute of Radiology
doi: 10.1259/bjr/25402966
British Journal of Radiology 82 (2009),e1-e2 ©2009 The British Institute of Radiology
An abdominal muscular fold mimicking tumour
ÖZTOPRAK, MD
B ÖZTOPRAK, MD
C GÜMÜ
, MD
H E
LMEZ, MD
and
M F ERKOÇ, MD
Cumhuriyet University Faculty of Medicine, Department of Radiology, 58140 Sivas, Turkey
Correspondence: brahim Öztoprak, Cumhuriyet University Faculty of Medicine, Department of Radiology, 58140 Sivas, Turkey. E-mail: oztoprak{at}cumhuriyet.edu.tr
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Abstract
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Mass-like lesions and anatomical variations sometimes create challenges for diagnosis in both clinical and radiology practice. We present a "pseudomass" originating from the right abdominal wall in a 75-year-old patient with invasive ductal carcinoma of the breast. Age-related structural changes in the abdominal wall, as well as anatomical variations, should be kept in mind in order to establish the correct radiological diagnosis and to avoid unnecessary procedures.
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Introduction
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Similar to the soft tissues in other parts of the body, abdominal muscles can show degenerative changes with ageing. These changes include loss of elasticity and muscle atrophy, potentially resulting in change to the course or orientation of the muscle.
To the best of our knowledge, age-related abdominal muscle changes simulating a focal mass have not been reported before. We present the CT findings of a mass-like lesion originating from the right internal oblique abdominal muscle in a patient who was referred to the radiology department for CT-guided needle biopsy with a provisional diagnosis of a metastatic tumour.
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Case report
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A 75-year-old woman who had undergone surgery for breast cancer in the previous year was admitted to our hospital for a routine follow-up. As part of her medical history, she had undergone a uterine myomectomy 25 years before, and was receiving antihypertensive treatment. She had noticed a lump in her left breast one and a half years earlier, and following mammography had excisional biopsy followed by modified radical mastectomy. A Grade 1 invasive ductal carcinoma of the breast was confirmed by histopathological examination of the surgical specimen. On her last admission, a contrast-enhanced abdominal CT obtained with a routine protocol showed a lobulated mass, approximately 2 x 2 x 2 cm in size, on the right upper abdominal wall originating from the internal oblique abdominal muscle (Figure 1
). The mass was isodense to muscle and intra-abdominal extension was not observed, although a mild indentation was noted on the inferolateral portion of the right lobe of the liver owing to the mass effect of the lesion. The transverse abdominal muscle was deplaced medially, whereas the course of the external oblique abdominal muscle was not affected. The CT findings were thought to be of a mass in the abdominal wall. A metastasis from invasive ductal carcinoma of the breast was considered in the differential diagnosis, and a CT-guided biopsy was planned.
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Figure 1. Contrast-enhanced multidetector CT image shows a lobulated mass continuous with the internal oblique abdominal muscle. The mass is isodense with the musculature. The fat planes between the three layers of anterolateral abdominal muscle are not obscured. The transverse abdominal muscle is deplaced medially. An indentation on the inferior aspect of the right lobe of the liver is also noted. No sign of intra-abdominal extension or infiltration is present.
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CT images were obtained with the patient in a left lateral oblique position to determine the biopsy site prior to the intervention. Surprisingly, the mass was not observed on these images, and all three layers of the anterolateral muscle group appeared normal (Figure 2). Thereupon, the patient was rescanned in the supine position to make sure that the lesion had not been missed in the oblique position; the mass reappeared at the same site where it had been first detected (Figure 3). The mass, actually the "pseudomass", was similar to the one detected on initial CT imaging, but was not exactly the same because the images were obtained immediately after the patient was positioned on her back, before the abdominal muscles had had enough time to become rearranged. As a result, the tumour-like appearance on the anterolateral abdominal wall was interpreted as age-related muscular changes.
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Figure 2. Pre-procedure unenhanced CT image at the level of the renal veins, obtained with the patient in a left lateral oblique position, does not reveal any mass. All three layers of anterolateral abdominal muscle appear normal. Note the indentation on the liver has also disappeared.
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Figure 3. Repeated unenhanced CT image obtained in the supine position at the same level shows recurrence of the mass-like lesion, although not exactly in the same configuration as in Figure 1 .
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Discussion
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Four main muscular layers constitute the anterior abdominal wall along with the cutaneous, fibrous and adipose tissues. The rectus abdominis muscle forms the anteromedial abdominal wall. The most superficial layer of the anterolateral wall is formed by the external oblique abdominal muscle, and the internal oblique abdominal muscle underlies this. The transverse abdominal muscle constitutes the innermost layer of the anterolateral musculature [1].
The most important consequence of ageing is the loss of muscle mass, also called sarcopenia, which results from decreased physical activity and myopathic and neuropathic alterations [2]. The atrophic changes involve both the muscle fibre area and the fibre number. Age-related changes in the abdominal wall musculature have not been described; however, generally, muscular atrophy is characterized by loss of volume and fatty involution of the muscle [3]. The muscle bulk on the right side of the abdominal wall appeared very similar to the unaffected side in our case. Therefore, the role played by atrophy in the occurrence of this mass-like appearance and the reasons why the contralateral side was not affected were not clear. A history of trauma, operation or infection involving that area was absent from our patient, thus the changes in the muscle were suggestive of age-related loss of elasticity and strength, and increased vulnerability to the effects of gravity. However, normal asymmetry of muscle folds or an alteration in the disposition of tissues owing to weight loss should also be considered.
Distant metastases to the abdominal wall are extremely rare, and abdominal wall metastases from breast cancer theoretically occur because of the seeding of tumour cells after resection or fine needle aspiration biopsy of an intraabdominal metastasis [4]. The disappearance of the lesion with repositioning easily ruled out a metastasis in our patient.
In conclusion, we suggest that age-related changes, alterations in the disposition of tissues and anatomical variations in the soft tissues should be kept in mind when evaluating mass lesions in order to avoid unnecessary procedures.
Received for publication August 29, 2007.
Revision received November 11, 2007.
Accepted for publication November 23, 2007.
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References
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- Williams PL, Warwick R, Dyson M, Bannister L. Gray's anatomy. 37th edn. London, UK: Churchill Livingstone, 1989:545–659.
- Proctor DN, Balagopal P, Nair KS. Age-related sarcopenia in humans is associated with reduced synthetic rates of specific muscle proteins. J Nutr 1998;128(Suppl):351S–55S.
- Yao L, Mehta U. Infraspinatus muscle atrophy: implications? Radiology 2003;226:161–4.[Abstract/Free Full Text]
- David O, Kluskens L, Reddy V, Kluskens L, Bitterman P, Attal H, et al. Malignant cutaneous and subcutaneous abdominal wall lesions: a fine-needle aspiration study. Diagn Cytopathol 1998;19:267–9.[Medline]
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Abstract
Introduction
