Endosonographic characteristics of submucosal tumors (SMT).
Approach and algorithm

M. J. Varas Lorenzo

Unit of Eco-Doppler and Ecoendoscopy. Centro Médico Teknon.
Unit of Ecoendoscopy. Centro Internacional de Medicina Avanzada (CIMA). Barcelona, Spain
AED Action Protocol for Gastrointestinal Ultrasonography. Coordinators: M. Gómez Rubio, MD and José Souto Ruzo, MD.

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Varas Lorenzo MJ. Endosonographic characteristics of submucosal tumors (SMT). Approach and algorithm. Rev Esp Enferm Dig 2004; 96: 215-218.

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Recibido: 29-12-03.
Aceptado: 12-01-04.

Correspondencia: M. J. Varas Lorenzo. Unidad de Eco-Doppler y Ecoendoscopia. Centro Médico Teknon. Unidad de Ecoendoscopia. Centro Internacional de Medicina Avanzada (CIMA). Barcelona

 

INTRODUCTION

Submucosal lesions (SMLs) of the upper gastrointestinal tract (1-4) represent a significant diagnostic and therapeutic challenge to both endoscopists and gastroenterologists. Such lesions may be assessed by using multifrequency transendoscopic miniprobes, or endoscopic ultrasonography (EUS), either radial or linear.

Fine-needle puncture-aspiration (FNA) of SMTs should be guided by only linear EUS.

EUS YIELD

Submucosal lesions or abnormalities:

1. Can EUS or endoscopic ultrasonography recognize submucosal lesions and differentiate between extrinsic compression (spleen, liver, etc.) and gastrointestinal submucosal tumors?

Yes, it can with a sensitivity greater than 90% (3,5). According to our group's cumulative experience (more than 140 cases), sensitivity was 94%.

2. Can EUS recognize a lesion's exact origin, size, and ultrasonographic pattern?

Yes, EUS can establish whether a tumor is within the gastrointestinal wall or otherwise. Regarding submucosal tumors (lipomas, myoid tumors), EUS can identify the layer a tumor originates in as well as its size, and is also a good technique for the investigation of gastroesophageal SMT endosonographic pattern (score of 9 at Monaco Consensus in 2000) (4). It also successfully differentiates liquid from solid lesions.

3. Can EUS differentiate between benign and malignant (stromal) SMTs?

It can be done with a sensitivity above 80% (6-8). EUS was assigned a score of only 6 at the Consensus Meeting held in 2000 (4).

Classic malignant characteristics include: size greater than 3 cm, nodular shape, irregular borders, surface ulceration, heterogeneous pattern, and presence of anechoic foci indicating intratumor necrosis (6). According to the experience collected by us and other authors (7), benign SMTs are usually smaller than 4 cm in size. The likelihood of malignancy is 0-11% when none of the following signs are present: size greater than 4 cm, irregular borders, echogenic foci greater than 3 mm in size, and cystic foci greater than 4 mm in size. Should more than two of these signs be present, the likelihood of malignancy rises to 80-100% (7). The finding of irregular borders, cystic shapes, or presence of adenopathies indicates malignancy with a positive predictive value (PPV) of 100% (8).

4. Which is the role of transendoscopic miniprobes (MPs) in assessing SMTs?

Two independent studies demonstrated that accord between EUS and MPs was very high. In our experience, the sensitivity of EUS and MP was 95%, and accord was almost 100% (10). Therefore, we feel that MPs may be safely used in daily clinical practice to assess SMTs, as most of these lesions are usually benign (9), small in size (less than 2 cm), and not in need of any treatment. 5. How are SMTs approached and managed? An algorithm? (Fig. 1).

Once an imaging technique (radiography, ultrasonography, computerized tomography, magnetic resonance imaging, endoscopy) has detected the presence of a submucosal lesion, EUS must be unavoidably used to definitely confirm the presence of an SMT, attempt to characterize the lesion's histology, and orient regarding its bening or malignant nature. Studies will be terminated if the finding is a compression or a cystic or lipomatous SMT.

Otherwise, surveillance with yearly follow-up or treatment by either endoscopic or surgical means is recommended, following a previous FNA with immunohistochemical testing [CD34, c-kit (CD117, Ki-67)] (11,12). Biopsy and FNA are of limited value, particularly for gastrointestinal stromal tumors (GISTs). A classification to predict aggression based on size, site, and mytotic index has been proposed for these tumors (13).

Symptomatic SMTs (bleeding, obstruction, etc.) smaller than 2-3 cm in size and originating in the second or third layer of the gut are eligible for endoscopic resection (14,15) with low risk. Approximately, 75% of resected hypoechogenic SMTs are in fact GISTs, and at least 5% of them are malignant (9).

CONCLUSION

EUS is essential in the assessment of SMLs. Most SMTs are benign and need not be treated. FNA may be used for cases not properly characterized by ultrasonography or doubtful. It is of limited value for GISTs. EUS-provided information may help decide on either endoscopic or surgical treatment.

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