Case report

Smooth muscle tumors of the esophagus: clinicopathological ®ndingsin six patients

H. Kimura1, K. Konishi1, T. Kawamura1, N. Nojima1, T. Satou1, M. Kaji1, K. Maeda1, K. Yabushita1,M. Tsuji1, A. Miwa2

Departments of 1Surgery and 2Pathology, Toyama Prefectural Central Hospital, Toyama, Japan

SUMMARY. Preoperatively, it is di�cult to discriminate leiomyoma and leiomyosarcoma of the esophagus, whichare rare smooth muscle tumors. The objective of this study was to evaluate the clinicopathological ®ndings of thisunusual lesion. A search of the surgery archives of the Toyama Prefectural Central Hospital of Pathology revealedsix cases of esophageal smooth muscle tumors. Clinicopathological ®ndings were reviewed retrospectively. Onlythree patients (50%) presented with dysphagia, and the remaining three patients were asymptomatic. Thesepatients underwent surgical excision. Histologically four of the six tumors were leiomyomas, and the other twotumors were leiomyosarcomas. Two tumors were in the upper to middle esophagus, and the remaining four were inthe distal esophagus. On endoscopic examination, all tumors were noted to be polypoid. The two leiomyosarcomasmeasured over 5 cm and the four leiomyomas less than 4 cm. Neither ulceration nor necrosis proved to be of use indiscriminating leiomyoma and leiomyosarcoma. The two patients with leiomyosarcoma died of liver metastasis 10and 22 months after the treatment. Patients with leiomyosarcoma presented with distant metastasis and/orrecurrence, with hematogeneous metastasis being the predominant type of recurrence.

INTRODUCTION

Smooth muscle tumor is the most common of thepure mesenchymal tumors of the esophagus. It hasbeen di�cult in some smooth muscle tumors of thedigestive tract (leiomyomas, leiomyoblastomas andleiomyosarcomas) to predict their biologic behavioraccording to histopathologic ®ndings only. Attemptshave been made to pathologically di�erentiate benignfrom malignant smooth muscle tumors by a varietyof criteria for the malignancies, such as tumor size,cellularity and mitotic index.1-3 Recently, we havesurgically treated six patients with primary esopha-geal smooth muscle tumors, including two cases ofleiomyosarcoma and four cases of leiomyoma. Thispaper reports the ®ndings in a study of clinico-pathologic features of leiomyoma and leiomyosarco-ma of the esophagus.

MATERIAL AND METHODS

Six patients with smooth muscle tumors of theesophagus (four with leiomyoma and two withleiomyosarcoma) treated at the Department of Sur-gery, Toyama Prefectural Central Hospital, duringthe period from 1973 to 1996, were chosen for thestudy. They comprised three male and three femalepatients, aged 37±69 years (mean 55.2 years). Each ofthem was examined for tumor location, tumor size,macroscopic type and prognosis. All tissue sampleswere formalin ®xed.

All patients underwent barium examination andupper endoscopy. Biopsies were performed on thesepatients. These same patients also had a computedtomographic scan of the mediastinum and liver.

RESULTS

Table 1 shows the diagnostic process of the sixpatients, arranged in order of the location and sizeof the tumor. Only three patients (50%) showedsymptoms that might be related to the upper alimen-tary tract (all three patients had dysphagia), and theremaining three patients were asymptomatic. These

Address correspondence to: H. Kimura, Department of Surgery,Toyama Prefectural Central Hospital, 2-2-78, Nishinagae, Toyama930-8550, Japan. Tel: (+81) 764 24 1531; Fax: (+81) 764 22 0667.

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Diseases of the Esophagus (1999) 12, 77±81Ó 1999 ISDE/Blackwell Science Asia

three patients, free of esophageal symptoms, werediagnosed by chance: two patients were diagnosed bya thorough medical examination, and the remainingone was diagnosed when he underwent an examina-tion for another digestive disease.

In this series, the most frequent location of thetumor was in the middle to lower third of theesophagus. Two tumors were in the upper to middleesophagus, and the remaining four were in the distalesophagus. On endoscopic examination, all tumorswere noted to be polypoid. The two leiomyosarcomasmeasured over 5 cm and the four leiomyomas lessthan 4 cm. Ulceration was recognized in one (case 1)of the two leiomyosarcomas, and in one (case 4) ofthe four leiomyomas. Necrosis was recognized in one(case 1) of the leiomyosarcomas and in one (case 5) ofthe leiomyomas. Neither ulceration nor necrosisproved to be of use in discriminating betweenleiomyoma and leiomyosarcoma.

The preoperative diagnoses were as follows: onefor carcinoma, four for smooth muscle tumor andone for achalasia (Table 2). All patients underwentsurgical excision, and an enucleation of liver metas-tasis was performed for one patient (case 1). Twopatients with leiomyosarcoma died of liver metastasis10 and 22 months after the treatment.

CASE REPORTS

Case 1: leiomyosarcoma

A 69-year-old man presented with a 5-month historyof dysphagia. Physical examination revealed anemia.He was initially investigated for an esophagealmalignancy by barium swallow (Fig. 1), and subse-quently by esophagoscopy (Fig. 2) and computedtomographic (CT) scanning of the chest and liver. Onendoscopic examination, the tumor was located in thedistal esophagus and was polypoid. Multiple biopsyspecimens of the esophageal tumor were obtained,and squamous cell carcinoma was suspected. Solitaryliver metastasis was found on subsequent staging(Fig. 3). Even if metastasis was present, a palliativeresection could still be performed, because the patienthad severe dysphagia. The patient underwent atranshiatal esophagectomy, gastric interposition, pos-terior mediastinal esophagogastrostomy and enucle-ation of liver metastasis.

PathologyMacroscpically, the primary nodular and ulceratedtumor measured 8 ´ 4 ´ 1.8 cm (Fig. 4), and themetastatic tumor weighed 54 g and measured5 ´ 5 ´ 3 cm. Microscopically, the tumor had inter-

Table 1. Characteristics of six esophageal smooth muscle tumors

GrossAppearance

Case Age/sex Symptoms Location behavior Size (cm) Ulcer Necrosis Calci®cation

1 69/M Dysphagia Lower Polypoid 8.0 ´ 4.0 + + )

2 61/M None Middle Polypoid 5.5 ´ 4.5 ) ) )

3 56/M None Middle Polypoid 2.5 ´ 2.5 ) ) )

4 37/M Dysphagia Lower Polypoid 2.5 ´ 1.5 + ) )

5 67/F Dysphagia Lower Polypoid 3.5 ´ 2.5 ) + +

6 41/F None Lower Polypoid 2.0 ´ 2.0 ) ) )

Table 2. Esophageal smooth muscle tumors: treatment and survival

CasePreoperativediagnosis Operation

Site of recurrenceor metastasis Survival (months)

1 Cancer Esophagectomy Liver 10, DODEnucleation ofliver metastasis

2 SMT Esophagectomy Liver 22, DOD3 SMT Esophagectomy None 31, AWD4 Achalasia Partial resection None 108, AWD5 SMT Partial resection Unknown6 SMT Esophagectomy None 221, AWD

SMT, smooth tumor: DOD, dead of disease: AWD, alive without disease.

78 Diseases of the Esophagus

lacing bundles of markedly anaplastic pleomorphicspindle cells (Fig. 5). The tumor cells were uniformlypositive for desmin and a-smooth muscle actin(SMA), whereas they were negative for S-100 proteinor neuron-speci®c enolase (NSE). Resected livermetastasis showed leiomyosarcoma similar to theprimary tumor.

Clinical courseThe patient died of liver metastasis 10 months afterthe primary treatment.

DISCUSSION

Smooth muscle tumor of the esophagus is a rarelesion. It is the most common tumor of the esoph-agus4 and, therefore, diagnosis and management ofthis tumor, which may not be straightforward, isimportant to surgeons. Pure sarcomas of the esoph-agus are very rare. The most common of these isleiomyosarcoma of smooth muscle origin. At the timeof this report, about 100 cases of esophageal lei-omyosarcoma had been previously recorded in Ja-pan.5±7 The diagnosis of a malignant soft-tissue

Fig. 1ÐX-ray examination of the esophagus.

Fig. 2ÐEndoscopic examination of the esophagus.

Fig. 3ÐComputed tomographic scanning of the liver.

Fig. 4ÐMacroscopic view of the resected tumor.

Fig. 5ÐHistologic ®ndings of the resected tumor (HE ´ 4.5).

Smooth muscle tumors of the esophagus 79

tumor (sarcoma), especially in the gastrointestinal(GI) tract, is riddled with a number of questionsregarding the true nature of such a tumor. A largebody of recent literature has addressed these ques-tions and strongly recommended the application ofimmunocytochemistry for the precise de®nition ofsarcomas in the gastrointestinal (GI) tract.8±14 Manyrecent studies found that desmin and SMA wereuseful for con®rming a histologic impression ofentrapment of smooth muscle bundles.8±10 Converse-ly, stromal tumors are positive for S-100 protein, andschwannomas are positive for NSE.11±13 The tumorcells in our cases were positive for desmin and SMA,whereas they were negative for S-100 protein or NSE.

Dysphagia is by far the most common complaintin all series, including ours.4,14 Seremetis et al4 foundthat 47.5% of 838 patients had dysphagia and 45%reported pain. Bleeding occurred rarely. Somesmooth muscle tumors are diagnosed by chest radio-graph on asymptomatic patients. In our series half ofthe patients were asymptomatic. Although only oneof our patients had a diagnostic chest radiograph(case 2), the literature does contain reports ofleiomyosarcoma presenting as mediastinal masses inotherwise asymptomatic patients.15

On endoscopic examination, all tumors were notedto be polypoid. Leiomyoma and leiomyosarcomausually in the middle or distal portions of theesophagus, where the smooth muscle is located. Inthe past, esophageal leiomyosarcoma has been clas-si®ed as polypoid in 60% of cases and as in®ltrative in40%.16,17 As for the radiographic ®ndings in lei-omyosarcoma of the esophagus, Levine et al15

reported that esophageal leiomyosarcoma has radio-graphic features similar to those of leiomyosarcomafound elsewhere in the GI tract. Barium studies mostcommonly revealed large intramural masses that hada marked exophytic component and often containedareas of ulceration or tracking.

It is important to be aware of the limitations ofendoscopy in diagnosing esophageal leimyoma orleiomyosarcoma.14,18 When the intraluminal masscontains ulcerations or erosions, as in our patient(case 1), it is di�cult to di�erentiate such a tumorfrom squamous cell carcinoma. If the overlayingmucosa is intact, however, false-negative biopsyspecimens may be obtained.19 In our patients,endoscopy could not con®rm the presence ofesophageal leiomyosarcoma in one of two patients.The super®cial nature of the biopsy specimensprecludes an accurate histologic diagnosis in manypatients with this tumor.

In this series, all tumors were noted to be polypoid.Two leiomyosarcomas measured over 5 cm and fourleiomyomas measured less than 4 cm. Ulceration wasrecognized in one of two leiomyosarcomas, and oneof four leiomyomas. Necrosis was found in one of theleiomyosarcomas and one of the leiomyomas. Neither

ulceration nor necrosis could discriminate betweenleiomyoma and leiomyosarcoma. Furthermore, endo-scopic biopsy may also be non-speci®c. Newermethods for evaluating these lesions include endo-scopic ultransonography (EUS). Aimoto et al 20 ®rstdescribed the typical EUS ®ndings of esophagusleiomyosarcoma: a well-de®ned, hyperechoic, homo-geneous mass with scattered strong echoes originatedfrom the muscular layer.

Leiomyosarcoma has a slow and indolent clinicalcourse, followed by late recurrence and eventualdeath of patients from the disease. Hematogenousmetastasis was the cause for the majority of tumorrecurrences.21 Our two patients with leiomyosarcomadied of liver metastasis 10 and 22 months after thetreatment. Esophagectomy or esophagogastrectomyis a surgical choice. Even if metastases are present, apalliative resection can still be performed. In patientswith leiomyoma, the de®nitive treatment may consistof thoracotomy and enucleation of the tumor in mostcases. The morbidity and mortality results are lowand symptomatic relief is excellent.

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