A clinicopathologic and immunohistochemical study of 16 patients with small intestinal leiomyosarcoma: Limited utility of immunophenotyping

Abstract

Clinicopathologic data including immunophenotypic expression of 16 new cases of small intestinal leiomyosarcoma are presented. Patient age ranged from 27 to 87 years (mean, 61 years) with a 2.2:1 male-female ratio. Eighty-eight percent of tumors occurred distally, i.e., in the jejunoileum. Considerable histologic heterogeneity was noted including epithelioid, myxoid, and sclerotic variants. Stratification by histologic grade suggests important clinical subsets. Only in grade I tumors is surgical extirpation alone potentially curative. Grade II tumors are associated with meaningful survival usually measured in years, however, nearly all patients can be expected to die from their tumors. Grade III sarcomas are fully malignant and rapidly progressive: except for one case with limited follow-up, all patients with Grade III sarcomas died of disease with a mean survival of only nine months (median, 2 months). Immunostaining with antibodies directed against vimentin, muscle-specific actin, desmin, and S-100 protein were performed. Only antivimentin was uniformly reactive. Sixty-three percent of cases tested showed actin immunoreactivity, and no tumors revealed immunohistochemically detectable desmin or S-100 protein. Although many small bowel stromal sarcomas appear "poorly differentiated" by immunohistochemical methods presently available, that they are indeed leiomyosarcomas seems most likely from their intramural location and light histologic study. The limited utility of immunophenotyping and the importance of histologic grading are stressed.

The reappraisal of gastrointestinal stromal tumors: from Stout to the KIT revolution

“…It is interesting to note that for more than two decades, until the advent of ultrastructural examination and subsequently of immunohistochemistry, these tumors were generally regarded as deriving from smooth muscle cells and were therefore variably classified as leiomyomas, bizarre leiomyomas [54], cellular leiomyomas [3], leiomyoblastomas, and leiomyosarcomas. Unfortunately, with the advent of electron microscopy and immunohistochemistry, unequivocal smooth muscle differentiation was hardly demonstrable in most cases examined [45,61]. In consideration of such an "orphan" phenotype Mazur and Clark [32] in 1983 pragmatically pioneered the use of the more generic designation "stromal tumor."…”

Spindle cell tumour with glandular elements: an unusual ileal neoplasm

“…Although appearing low grade, our case showed only focal desmin expression. High-grade leiomyosarcomas may show no or minimal desmin expression,4 but leiomyomas usually show diffuse desmin positivity. Despite this, our patient expressed other smooth muscle markers (smooth muscle actin, smooth muscle myosin heavy chain and h-caldesmon), and no other line of differentiation was identified in the spindle cell component.…”

Correspondence and Short Communications

“…This may be a future diagnostic tool. Immunohistochemical studies have been of limited help in establishing the diagnosis (12). The criteria for malignancy was, in our case, fulfilled with the demonstration of mitoses well above the minimum number of 5 per 10 high power fields (13).…”