Perivascular epithelioid cell tumors (PEComas)
Updates to Article Attributes
Perivascular epithelioid cells tumours (PEComas) are a group of related mesenchymal tumours and tumour-like conditions found in many locations. This group includes:
-
clear cell myomelanocytic tumour (CCMMT)
of the falciform ligament / ligamentum teres
-
unusual clear tumours of other organs
rectum
abdominal serosa
uterus: considered one of the commonest sites of involvement in the female pelvis
vulva
heart
orbit
Epidemiology
PEComas are far more common in females 4.
Associations
Pathology
HistologyMicroscopic appearance
All PEComas share similar and distinctive cellular morphology – peripheral epitheloid cells – which have no counterpart in normal tissue 4. These tumours appear as sheets and nests of epithelioid or spindle-shaped cells associated with blood vessel walls. They have granular eosinophilic cytoplasms.
ImmunohistochemistryImmunophenotype
PEComas are characterised by immunoreactivity to smooth muscle and melanocytic markers 4.
smooth muscle: actin, desmin
melanocytic: HMB-45, melan-A
Radiographic features
Unfortunately, due to non-specific imaging appearances and the scarcity of reported cases, no specific imaging features are recognised. These lesions seem to usually be solid but can be centrally necrotic 5-7. They generally demonstrate prominent contrast enhancement 6.
Treatment and prognosis
PEComas usually behave in a benign fashion although local recurrence and even malignant behaviour are encountered, mimicking malignant sarcomas. Surgical excision is usually curative.
Differential diagnosis
The differential diagnosis is broad and largely depends upon the location of the mass.
-<li><a href="/articles/renal-angiomyolipoma">angiomyolipoma (AML)</a></li>-<li><a href="/articles/clear-cell-tumour-of-the-lung">clear cell 'sugar' tumour of the lung</a></li>-<li><a href="/articles/lymphangioleiomyomatosis-1">lymphangioleiomyomatosis (LAM)</a></li>- +<li><p><a href="/articles/renal-angiomyolipoma">angiomyolipoma (AML)</a></p></li>
- +<li><p><a href="/articles/clear-cell-tumour-of-the-lung">clear cell "sugar" tumour of the lung</a></p></li>
- +<li><p><a href="/articles/lymphangioleiomyomatosis-1">lymphangioleiomyomatosis (LAM)</a></p></li>
-<a href="/articles/ccmmt">clear cell myomelanocytic tumour (CCMMT)</a><ul><li>of the falciform ligament / ligamentum teres</li></ul>- +<p><a href="/articles/ccmmt">clear cell myomelanocytic tumour (CCMMT)</a></p>
- +<ul><li><p>of the falciform ligament / ligamentum teres</p></li></ul>
-<li>unusual clear tumours of other organs<ul>-<li><a href="/articles/pancreatic-pecoma-1">pancreas</a></li>-<li>rectum</li>-<li>abdominal serosa</li>-<li>uterus: considered one of the commonest sites of involvement in the female pelvis</li>-<li>vulva</li>-<li>heart</li>-<li>orbit</li>- +<li>
- +<p>unusual clear tumours of other organs</p>
- +<ul>
- +<li><p><a href="/articles/pancreatic-pecoma-1">pancreas</a></p></li>
- +<li><p>rectum</p></li>
- +<li><p>abdominal serosa</p></li>
- +<li><p>uterus: considered one of the commonest sites of involvement in the female pelvis</p></li>
- +<li><p>vulva</p></li>
- +<li><p>heart</p></li>
- +<li><p>orbit</p></li>
-</ul><h4>Epidemiology</h4><p>PEComas are far more common in females <sup>4</sup>. </p><h5>Associations</h5><ul><li><a href="/articles/tuberous-sclerosis">tuberous sclerosis complex </a></li></ul><h4>Pathology</h4><h5>Histology</h5><p>All PEComas share similar and distinctive cellular morphology – peripheral epitheloid cells – which have no counterpart in normal tissue <sup>4</sup>. These tumours appear as sheets and nests of epithelioid or spindle-shaped cells associated with blood vessel walls. They have granular eosinophilic cytoplasms. </p><h5>Immunohistochemistry</h5><p>PEComas are characterised by immunoreactivity to smooth muscle and melanocytic markers <sup>4</sup>.</p><ul>-<li>smooth muscle: <a href="/articles/smooth-muscle-actin">actin</a>, desmin</li>-<li>melanocytic: HMB-45, melan-A</li>-</ul><h4>Radiographic features</h4><p>Unfortunately, due to non-specific imaging appearances and the scarcity of reported cases no specific imaging features are recognised. These lesions seem to usually be solid but can be centrally necrotic <sup>5-7</sup>. They generally demonstrate prominent contrast enhancement <sup>6</sup>. </p><h4>Treatment and prognosis</h4><p>PEComas usually behave in a benign fashion although local recurrence and even malignant behaviour are encountered, mimicking malignant sarcomas. Surgical excision is usually curative. </p><h4>Differential diagnosis</h4><p>The differential diagnosis is broad and largely depends upon the location of the mass.</p>- +</ul><h4>Epidemiology</h4><p>PEComas are far more common in females <sup>4</sup>. </p><h5>Associations</h5><ul><li><p><a href="/articles/tuberous-sclerosis">tuberous sclerosis complex</a></p></li></ul><h4>Pathology</h4><h5>Microscopic appearance</h5><p>All PEComas share similar and distinctive cellular morphology – peripheral epitheloid cells – which have no counterpart in normal tissue <sup>4</sup>. These tumours appear as sheets and nests of epithelioid or spindle-shaped cells associated with blood vessel walls. They have granular eosinophilic cytoplasms. </p><h5>Immunophenotype</h5><p>PEComas are characterised by immunoreactivity to smooth muscle and melanocytic markers <sup>4</sup>.</p><ul>
- +<li><p>smooth muscle: <a href="/articles/smooth-muscle-actin">actin</a>, desmin</p></li>
- +<li><p>melanocytic: HMB-45, melan-A</p></li>
- +</ul><h4>Radiographic features</h4><p>Unfortunately, due to non-specific imaging appearances and the scarcity of reported cases, no specific imaging features are recognised. These lesions seem to usually be solid but can be centrally necrotic <sup>5-7</sup>. They generally demonstrate prominent contrast enhancement <sup>6</sup>. </p><h4>Treatment and prognosis</h4><p>PEComas usually behave in a benign fashion although local recurrence and even malignant behaviour are encountered, mimicking malignant sarcomas. Surgical excision is usually curative. </p><h4>Differential diagnosis</h4><p>The differential diagnosis is broad and largely depends upon the location of the mass.</p>
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