both primary and secondary neoplasms can invove the abdominal wall.although large masses generally are discovered by inspection and palpation,small tumors may be difficult to detect clinically,particularly in obese patients or in those with surgical scars or indurated tissue.computed tomography is capable of demonstrating small abdominal wall tumors and may be valuable in defining the extent of palpable lesions for the purpose of placing radiotherapy ports and assessing the effectiveness of chemotherapy.computed tomography is also helpful in detecting tumor recurrence after surgical excision.
lipomas are common ,benign tumors that can be found throughout the body,including the subcutaneous fat or muscle layers of the abdominal wall.they are well-defined,homogeneous,fat attenuation(-40 to –100hu)masses that may contain thin soft tissue seota and vessels.
dismoid tumors are locally aggressive .benign fibrous tissue neoplasms
that occur most commonly in the musculoaponeurotic fascia of the anterior
abdominal and internal oblique muscles and their fascial covering.
approximately three fpurths of abdominal wall dismoids occur in women,
predominantly during the childbearing years.on precontrast ct images,
dismoids have an attenuation value similar to that of muscle,but they may
enhance on postcontrast ct scans to become hyperdence relative to
muscle.on mr images,dismoids commonly appear isointense to muscle
on t1-weighted images,variable in signal intensity on t2-weighted images,
and demonstrate diffuse enhancement after intravonous administration of
gadolinium.extensive fibrosis is suggested by areas of low signal intensity
on both t1-and t2-weighted images.these mr signal characteristics are
nonspcific,but suggestive in the proper clinical setting.the mutiplanar capability
of mri is helpful in defining the connection of the mass to the abdominal wall
muscle or fascia.
the most common primary malignant neoplasms of the abdominal wall are sarcomas,followed
in frequency by lymphomas.hematogenously spread metastases may involve either the
abdominal wall muscles or the subcutaneous fat.metastasic involvement of muscle produces
enlargment of the muscle,often with an associated alteration in normal attenuation value.
subcutaneous metastases usually are nodular,and are readily detected by ct as soft tissue
attenuation masses in the lower attenuation subcutaneous fat.direct spread to the abdominal
wall by an intraabdominal neoplasm appears as a thickening of the muscles with loss of the intermuscular and perimuscular fat planes.malignant neoplasms that spread intraperitoneally
,such as ovarian and gastrointestinal carcinoma,have a tendency to involve the umbilical
region,producing periumbilical masses.abdominal wall metastases of colon,ovarian,gastric
,and gallbladder carcinomar have been reported in incisions and port sites after laparoscopy.
differentiation of abdominal wall neoplasm from abscess or hematoma may not be possible
using ct criteria alone and clinical correlation is offen necessary.percutaneous needle biopsy
under ct guidance may be required to differentiate among these entities.
发表于 2005-4-19 08:48
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