Leiomyoma Workup

Updated: May 23, 2018
  • Author: Fnu Nutan, MD, FACP; Chief Editor: William D James, MD  more...
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Workup

Laboratory Studies

The measurement of hemoglobin and/or hematocrit levels might be considered in patients with multiple leiomyomas because erythrocytosis is reported in rare cases.

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Imaging Studies

Imaging studies are not routinely performed for leiomyomas; however, angioleiomyomas do have characteristic findings on ultrasound and magnetic resonance images.

On ultrasound images, angioleiomyomas show well-defined margins and a homogeneous structure suggestive of their benign nature. On color Doppler, they show high resistance in intratumor arteries, suggesting the presence of muscular arteries. [22]  Doppler is useful in patient assessment before uterine artery embolization for uterine leiomyoma. [6]

MRI cannot differentiate between the different histological subtypes of angioleiomyomas; however, images show mixed hyperintense and isointense areas compared with skeletal muscle, with a hypointense rim corresponding to a fibrous capsule on T2-weighed images. [22, 25]

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Procedures

Tissue examination is necessary to establish the diagnosis. Therefore, a partial or excisional biopsy is indicated.

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Other Tests

Fumarate hydratase testing plays an important role in the diagnosis of patient with hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome. Its absence causes increased expression of ferritin 38. The gene whose heterozygous expression causes HLRCC is located on chromosome one and its activity can be tested with immunohistochemistry or the gene mutation itself can be tested. However, new reports have emerged in which the sensitivity of immunohistochemistry testing was seen to be low 39% and new novel mutations were found near the hot spot of the originally tested mutation. [26]

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Histologic Findings

Leiomyomas are smooth muscle tumors that are generally well differentiated. The characteristic smooth muscle nuclei are elongated with blunt ends, and they are often described as cigar or eel shaped. When these fibers are cut in cross-section, perinuclear vacuolization may be appreciated. With electron microscopy, the smooth muscle cells of a leiomyoma appear normal.

Piloleiomyomas occur mainly in the reticular dermis and are not encapsulated. The smooth muscle bundles of these tumors are interlaced with variable amounts of collagen. The rate of mitotic activity, if present, is low.

Genital leiomyomas are similar to piloleiomyomas in their histologic appearance.

In contrast, angioleiomyomas contain many dilated vascular spaces amidst smooth muscle bundles arranged in a more concentric fashion. These vascular spaces are lined by an endothelium. For further distinction, angioleiomyomas are well circumscribed or encapsulated and contain minimal collagen. In addition, larger angioleiomyomas frequently have areas of mucinous alteration.

Three histologic subtypes of angioleiomyomas are based on differences in the vascular channels: solid or capillary, cavernous, and venous. The solid or capillary type contains many small vascular spaces. Cavernous tumors have dilated vascular spaces with only small amounts of smooth muscle. The venous subtype contains veins with thick muscular walls.

Special stains can be used to distinguish smooth muscle from collagen, both of which are pink-red with hematoxylin-eosin stain. The Masson trichrome stain highlights smooth muscle as dark red and collagen as blue-green. With aniline blue stains, smooth muscle appears red and collagen appears blue. A van Gieson stain results in yellow smooth muscle contrasted against red collagen. With phosphotungstic acid–hematoxylin (PTAH) stain, myofibrils are purple. Immunohistochemical staining for desmin and actin, markers of smooth muscle differentiation, can be performed to detect these markers in leiomyomas. Interestingly, the stromal cells within an angiomyoma lack the human progenitor cell antigen CD34. [27, 28]

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