Intermuscular lipoma in a 4-year-old child presenting like Spigelian hernia.

Lipomas are commonest benign tumor and can occur at any part of the body, but intermuscular lipomas are very rare and usually occur at middle age or later. Intermuscular lipomas remain hidden till they attain a large size. They commonly appear on anterior abdominal wall. We treated a case of intermuscular lipoma in a 4-year-old girl. It presented as a bulge at right iliac fossa during straining; its location and symptoms were similar to that of Spigelian hernia. Actual diagnosis was made under general anesthesia and complete surgical excision was done. This is a rare mode of presentation of an intermuscular lipoma. Intermuscular lipoma of the abdominal wall at this young age was not reported earlier.

INTRODUCTION

Intermuscular lipomas are rare and tend to develop in the anterior portion of the abdominal wall and rarely in the extremities. Unlike its common counterpart; subcutaneous lipomas which are conspicuous by their bumps, an intermuscular lipoma may not become obvious till it attains an enormous size or produces symptoms due to pressure affect. Intermuscular lipomas in children are extremely rare. We treated a case of intermuscular lipoma of the anterior abdominal wall in a 4-years-old girl, presenting like Spigelian hernia. To our knowledge, intermuscular lipoma of the abdominal at such young age was not reported earlier.

CASE REPORT

A 4-year-old girl was brought to us with history of a swelling at her anterior abdominal wall at right lower quadrant, which appeared only during crying, coughing, or straining; typical of an intermuscular hernia [Figure 1]. Parents observed it for last 3 months. The child was hyperactive and did not allow proper examination and no lump could be palpated. Ultrasonography did not show any lump or any other abnormality. Clinical diagnosis of Spigelian hernia was made and the patient was prepared for hernia repair. But under general anesthesia, one globular lump was palpable at the right iliac fossa. A transverse incision was made over the mass and further dissection revealed a lipomatous tumor between abdominal wall muscles. As dissection proceeded, muscle groups were separated and a dumb-bell shaped tumor was removed completely [Figure 2]. The mass was well-circumscribed and there was no infiltration into muscle groups. Histopathology of the tumor showed mature lipoma. Child recovered uneventfully. There was no recurrence during 3years postoperative follow-up period.

Figure 1

Bulge at right iliac fossa during crying

Figure 2

Intraoperative picture showing the dumb-bell shaped lump

DISCUSSION

Lipomas are one of the most commonly encountered benign mesenchymal tumors of mature adipose tissue and commonly found in subcutaneous plane in the extremities and trunk. Lipomas may occasionally be found within a muscle (intramuscular lipomas) or between muscles (intermuscular lipomas). They may be divided into infiltrative and well-circumscribed types. Intermuscular lipomas account for 0.3% of fatty tumors, arise predominantly in middle and late adult life, and occur most often in the anterior abdominal wall.[1] Lipomas that occur in the subcutaneous layers is the most noticeable, as they create visible bumps underneath the skin. Inter- and intramuscular lipomas lay within the body surface are not noticeable unless they grow to a large size. A large intermuscular lipoma may produce symptoms such as muscle aches or shooting pains, which can occur if the lipoma presses on a nerve. Ultrasonography is the initial diagnostic procedure employed, but it may not visualize the mass.[2] Though our case had a large intermuscular lipoma it was not obvious during normal activities of the child and even ultrasonography could not visualize the mass.

Spigelian hernia occurs through slit-like defect in the anterior abdominal wall adjacent to the semilunar line. Spigelian hernia can be congenital or acquired, but Spigelian hernia is in itself very rare. Most of Spigelian hernias occur in the lower abdomen where the posterior sheath is deficient.

The diagnosis of Spigelian hernia is difficult; few surgeons suspect it, it has no characteristic symptoms, and the hernia may be interparietal with no obvious mass on inspection or palpation. It may present as a swelling adjacent to the iliac crest. The patient may have a classic lump when he/she strains and disappears on lying down.

Presentation of our case was more like a Spigelian hernia than a tumor. Diagnosis of a Spigelian hernia is basically clinical. Ultrasound is recommended as first-line imaging investigation, but the correct diagnosis is not always obtained.[3] These hernias should be repaired because of the high risk of strangulation.[4]

After complete resection, there is 1% chance of recurrence for a usual lipoma as compared to 19% recurrence rate for an intermuscular lipoma,[5] which is most likely due to incomplete surgical excision, especially for an infiltrative type of intermuscular lipoma.[1] Thus, the possibility of recurrence after a long tumor-free period is probable, and therefore an extended period of follow-up is desirable.