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Fig. 1.31 Leiomyoma of oesophagus. A Haema-toxylin and eosin stain. B Immunoreactivity for desmin.

Clinical features

Dysphagia is the usual complaint, but many leiomyomas and a small proportion of stromal tumours are asymptomatic and are incidentally detected by X-ray as mediastinal masses. Since most sarcomas project into the lumen, they are relatively easy to diagnose by endoscopy or imaging studies. The endoscopic pattern is that of a submucosal tumour with a swelling of a normal mucosa. Endo-scopic ultrasound helps in determining the actual size of the tumour, its position in the oesophageal wall and its eventual position in the mediastinum. A CT scan of the mediastinum is then a useful compliment. Most tumours less than 3 cm in diameter are benign. Endoscopic tissue sampling (large biopsy or fine needle aspiration) is difficult and not very reliable for the assessment of malignancy.

Macroscopy

Leiomyomas vary in size from a few millimeters up to 10 cm in diameter (average 2-3 cm). They may be spherical, or when larger they can form sausage-like masses with a large longitudinal dimen sion or dumb-bell shaped masses with circular involvement {1712, 1228}. Large leiomyomas (over 0.5 kg) have been described {968}. Sarcomas, most of them representing malignant gastrointestinal stromal tumours (GISTs), are typically multinodular or less commonly plaque-like masses resembling sarcomas of the soft tissues. Many oeso-phageal sarcomas protrude into the mediastinum.

Histopathology

Leiomyoma is composed of bland spindle cells and shows low or moderate cel-lularity and slight if any mitotic activity. There may be focal nuclear atypia. The cells have eosinophilic, fibrillary, often clumped cytoplasm. Eosinophilic granu-locytes and spherical calcifications are sometimes present. Leiomyomas are typically globally positive for desmin and smooth muscle actin, and are negative for CD34 and CD117 (KIT) {1228}.

Fig. 1.32 Stromal tumour of the oesophagus, involving the oesophageal muscle layer beneath a normal mucosa.
Fig. 1.33 Granular cell tumour of oesophagus.

Leiomyosarcoma, a malignant tumour featuring differentiated smooth muscle cells, is rare in the oesophagus. In a recent series, such tumours comprised 4% of all combined smooth muscle and stromal tumours. They were large tumours that presented in older adults, and all patients died of disease. Diagnosis is based on demonstration of smooth muscle differentiation by a-smooth muscle actin, desmin or both, and lack of KIT expression {1228}. Stromal tumours (GISTs) are rare in the oesophagus, and comprise 20-30% of the combined cases of smooth muscle and stromal tumours. Like elsewhere in the digestive system, they predominantly occur in older adults between the 6th and 8th decades; oesophageal stromal tumours may have a male predominance. Most oesophageal examples are spindle cell tumours, and a minority are epithelioid. Oesophageal GISTs are identical with their gastric counterparts by their positivity for KIT and CD34, variable reactivity for smooth muscle actin and general negativity for desmin. Most are clinically malignant, and commonly develop liver metastases. The oeso-phageal tumours analyzed to date have shown similar c-kit mutations (exon 11) as observed in gastric and intestinal GISTs {1228}. The pathological features are described with gastric GISTs.

Granular cell tumours are usually detected endoscopically as nodules or small sessile polyps predominantly in the distal oesophagus {1216, 7}. Benign behaviour is the rule, but a case of malignant oesophageal granular cell tumour has been reported. The tumours are usually small, up to 1-2 cm in diameter, and are grossly yellow, firm nodules. Histologi-cally they are composed of sheets of oval to polygonal cells with a small central nucleus and abundant granular slightly basophilic cytoplasm. This is due to extensive accumulation of lysosomes filled with lamellar material. Granular cell tumours are typically PAS- and S100-pro-tein positive and negative for desmin, actin, CD34 and KIT. Tumours that encroach upon the mucosa may elicit a pseudocarcinomatous squamous hyper-plasia {862, 1710}.

Rhabdomyosarcoma has been reported in older adult patients in distal oesophagus. A few well-documented cases have shown features similar to embryonal rhabdomyosarcoma {2002}. Demonstration of skeletal muscle differentiation by the presence of cross-striations, electron microscopy, or immunohistochemistry is required for the diagnosis. Synovial sarcoma has been reported in children and in older adults. These tumours usually present as polypoid masses in the proximal oesophagus {168, 149}.

Kaposi sarcoma may appear as a mucosal or less commonly more extensive mural lesion, usually in HIV-positive patients. Histologically typical are spindle cells with vascular slit formations and scattered PAS-positive globules. The tumour cells are positive for CD31 and CD34.

Grading

Histological grading follows the systems commonly used for soft tissue tumours. Mitotic activity is the main criterion for grading stromal sarcomas and leiomyosarcomas, namely those tumours with over 10 mitoses per 10 HPF are considered high-grade.

Genetics

Somatic deletions and gene rearrangements involving the genes encoding alpha5 and 6 chains of collagen type IV have been described in oesophageal leiomyomatosis associated with Alport syndrome {1704, 1982} and in sporadic

Fig. 1.34 Kaposi sarcoma in a patient with acquired immunodeficiency syndrome.

leiomyoma {683}, whereas these tumours do not have c-kit gene mutations commonly found in GISTs {1018}. Comparative genomic hybridization studies have shown that oesophageal leiomyomas do not have losses of chromosome 14, as often seen in GIST, but instead have gains in chromosome 5 {450, 1664}. Oesophageal stromal tumours show similar c-kit mutations as observed in gastric and intestinal GISTs (see stomach mes-enchymal tumours) {1228}. Kaposi sarcoma is positive for human herpesvirus 8 by PCR.

Prognosis

The prognosis of oesophageal sarcomas, like carcinomas, is largely dependent on the size, depth of invasion, and presence or absence of metastasis.

Secondary tumours and melanoma of the oesophagus

Secondary tumours Definition

Tumours of the oesophagus that originate from but are discontinuous with a primary tumour elsewhere in the oesophagus or an extra-oesophageal neoplasm.

Incidence

Metastatic spread to the oesophagus is uncommon. An unusually high frequency (6.1% of autopsy cases) was reported from Japan {1249}.

Origin of metastases

The concept of intramural metastasis in oesophageal squamous cell carcinoma is discussed in the chapter on squamous cell carcinoma of the oesophagus. Neoplasms of neighbouring organs such as pharynx or gastric cardia {714} can spread to the oesophagus via lymphatics. Haematogenous metastases from any primary localization may occur. Reported primary sites include thyroid {335}, lung {1416, 1249}, breast {2143,

1249, 545}, skin {1569, 1203}, kidney {1956}, prostate {1318} and ovary {1249}.

Localization

The most common site of involvement is the middle third of the oesophagus.

Clinical features

The leading symptom is dysphagia, whereas achalasia and upper gastrointestinal bleeding with anemia are unusual {545}. Barium swallow examination, endoscopy, computed tomography and magnetic resonance imaging demonstrate in most cases a submucosal tumour, but any aspect resembling a primary oesophageal carcinoma may be observed {545, 1318, 714}.

Histopathology and predictive factors

Submucosal localization without invasion of the mucosa is characteristic for a metastasis. Early metastases of gastric and oesophageal tumours into the oesophagus may be local indicators of systemic spread {896, 714}. The pres ence of metastasis in the oesophagus is a sign of poor prognosis, but the outcome is much better when the primary tumour growth rate is slow, and when other metastases are excluded {1416, 1249}.

Melanoma

ICD-O Code 8720/3

Malignant melanoma in the oesophagus is much more commonly metastatic than primary. Primary oesophageal melanomas are usually polypoid and are clinically aggressive lesions {400, 353}. They are believed to arise from a zone of atypical junctional proliferation of melano-cytes and such a proliferation is often present adjacent to the invasive tumour, although it may not be observed in advanced disease. The histology of the invasive component is indistinguishable from cutaneous melanoma {409}. Growth is typically expansile rather than infiltra-tive.

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