 |  |  |  |  |  |  |
| | |||||||
| Discussion |
A 15 year old girl was admitted with acute onset pain in the right iliac
fossa since 2-3 days. There was no history of vomiting or fever. On examination,
there was tenderness with a diffuse, firm lump in the right iliac fossa. Laboratory
studies of blood, urine and stools were normal.
 |
 |
| Fig.
1 | Fig.
2 |
 |  |
Fig.
3 | Fig.
4 |
The soft tissue plane between mass and bowel was well seen. No reverberation
artifacts or specks of calcification were seen. On color Doppler study, the lesion
showed moderate vascularity.
 |  | |
Fig.
5 | Fig.
6 | |
 |  | |
Fig.
7 | Fig.
8 | |
 | ||
Fig.
9 | ||
Plain
and post contrast axial CT scan images were acquired. There was an approximately
three centimeter diameter solid, hyperdense mass in the right lumbar region. This
lesion showed homogenous enhancement on post contrast scans. The solid component
was associated with a cystic, thin walled lesion. The soft tissue planes between
the bowel loop and the mass were well preserved. There was no free fluid in the
abdomen nor was adenopathy seen The uterus was normal.
In comparison to
the ultrasound findings, the mass appeared to be located in a more cephalad position.
Hence, the ultrasound examination was repeated. This confirmed the mass to be
quite mobile within the abdominal cavity.
The differential diagnostic possibilities
considered were an atypical gastrointestinal stromal tumor or an ovarian tumor.
At surgery, the ovaries, the bowel along with the ileocecal junction and
appendix were normal. A solid tumor 4x5 cm in size was present on the omentum
along its margin. A cyst filled with straw colored fluid was present adjacent
to it. The mass was completely excised.
 |  | |
Fig.
10 | Fig.
11 | |
On
histopathology, the mass was reported as an inflammatory pseudotumor.
DISCUSSION:
Inflammatory pseudotumours
are rare benign lesions occurring in all age groups. They frequently simulate
a true neoplasm both clinically and morphologically - presenting a diagnostic
and therapeutic dilemma.
Inflammatory pseudotumour, inflammatory myofibroblastic tumor and plasma
cell granuloma are synonyms used to describe the entity of an inflammatory solid
tumor containing spindle cells, myofibroblasts, plasma cells and histiocytes.
These are postulated to be an aberrant response to tissue injury with myofibroblasts
as the primary cell type, with exaggerated inflammatory reparative reaction to
trauma or infection.
They virtually affect every anatomic region and
organ, the common sites being the lung, brain, eye, pericardium, heart, trachea,
lymph nodes, bladder, pelvis and the gastrointestinal tract. Cases involving the
alimentary tract are rare and their etiology obscure. Symptomatology varies depending
upon the site of involvement.
There are reports of association of pseudotumors of the alimentary tract with
Castleman's disease, Hodgkin's disease, peptic ulceration, Behcet's disease, chronic
infections (Campylobacter jejuni, Helicopbacter pylori), or following trauma or
surgery. Anaplastic lymphoma kinase (ALK), a hallmark of anaplastic large cell
lymphoma, has recently been implicated in the genesis of some inflammatory pseudotumors
in children and young adults. Some cases may be related to an infectious process
or represent the sequel of an infection. Recently, a proportion of inflammatory
pseudotumors occurring in the liver and spleen have been shown to represent a
peculiar form of Ebstein-Barr virus-associated follicular dendritic cell tumor.
Some other cases are myofibroblastic or fibroblastic neoplasms as evidenced by
demonstration of clonal cytogenetic abnormalities and the occasional occurrence
of metastases.
Radiological findings are nonspecific and difficult to distinguish
from other lesions. Beyond the commonly encountered cases of typical ascites,
peritonitis, fluid collection there is a wide spectrum of uncommon non neoplastic
conditions that may involve the peritoneal and sub peritoneal spaces. An inflammatory
pseudotumour must be considered as one of the diagnostic possibilities.
Microscopically, this solid tumor consists of inflammatory plasma cells, histiocytes,
and lymphocytes in a matrix of spindle-shaped myofibroblasts. These lesions can
be locally invasive, and are sometimes confused with sarcomas. The lack of mitosis
and nuclear atypia favors plasma cell granuloma. It is found that tumors expressing
hyperdiploid characteristics are more aggressive and should be closely watched
and regularly followed up for recurrence. Such recurrences are documented in 18%
to 40% of cases and appear to be more frequent in the extrapulmonary lesions,
which are larger than eight centimeters and are locally invasive.
Surgical resection remains
the treatment of choice. Radiotherapy has been described as an adjunct in unresectable
pulmonary lesions. Complete resection of recurrences is recommended. There are
rare reports of malignant transformation after successive recurrences. These lesions
represent a single pathologic entity with a spectrum of clinical behavior depending
on the site of origin.
Alimentary tract pseudotumors are rare and may mimic
other more common surgical problems. An aggressive surgical approach is necessary
as there is a limited role of other adjunctive modalities. It is important to
differentiate these lesions from sarcomas at the time of exploration. These patients
require a close follow up with clinical examinations and appropriate imaging studies.