perivascular tumor

Perivascular tumors, also known as Pericytic Tumors or PEComas, are a rare type of soft tissue tumor that begins in cells that wrap around blood vessels.

Characteristics

• These tumors can be benign (not cancer) or malignant (cancer)
• They can occur anywhere in the body
• Can occur in adults or children

Cellular Features

• Perivascular epithelioid cell tumors are composed of perivascular epithelioid cells, which are a type of cell that wraps around blood vessels
• These cells have clear to granular eosinophilic cytoplasm and focal perivascular accentuation
• They can also be spindled or polygonal in shape

Growth Patterns

• Perivascular tumors can show an infiltrative growth pattern, with sheets and nests being the most common
• Vascular invasion is also a notable feature of these tumors

Histopathological Findings

• The tumor shows an infiltrative growth pattern and vascular invasion
• Composed of polygonal or oval-shaped cells arranged around blood vessels, spindle cells arranged in fascicles, and round epithelioid cells with clear cytoplasm
• Multinucleated giant cells are also noted

Diagnostic Criterion

• The diagnostic criterion for perivascular epithelioid cell tumors appears to be exclusively histopathological
• Characterized by a proliferation of perivascular epithelioid cells and the coexpression of markers for smooth muscle and melanocytes.

These characteristics and features are based on the information provided in search results [11][12][13][14].

Signs and Symptoms of Perivascular Epithelioid Cell Tumors (PEComas)

Perivascular epithelioid cell tumors, also known as PEComas, are rare tumors that can occur in any part of the human body. The signs and symptoms of PEComas vary depending on their location and size.

Common Signs and Symptoms:

• A lump or swelling in the soft tissue of the body under the skin [3]
• Abnormal uterine bleeding or lower abdominal pain with a palpable mass, especially in cases of uterine PEComas [4]
• Vaginal bleeding or abdominal pain, depending on the location of the tumor [5]
• Gastrointestinal symptoms such as abdominal pain, bloating, abdominal discomfort, and vomiting, particularly in cases of gastrointestinal PEComas [7]
• Abnormal signs and symptoms that may include abnormal uterine bleeding, lower abdominal pain with a palpable mass, vaginal bleeding, or abdominal pain [8]

Other Possible Symptoms:

• Hypokalemia (low potassium levels) which can occur in some patients [2]
• Infections such as skin, and abdominal infections, especially in cases of PEComas that are not properly treated [2]

It's essential to note that some PEComas may not cause any symptoms at all and are only discovered accidentally during imaging tests or other medical procedures.

References:

[1] The name perivascular epithelioid cell tumor was first proposed in the early 1990s after researchers noticed shared cellular features between the various tumors that are now members of the PEComa grouping. These features are considered unique to these types of tumors, distinguishing them from other tumors.

[2] The potential of emerging new therapeutics for the treatment of perivascular epithelioid cell tumors (PEComa). ... skin,

Diagnostic Approaches for Perivascular Epithelioid Cell Tumors (PEComas)

Perivascular epithelioid cell tumors (PEComas) are rare and challenging to diagnose, often requiring a combination of clinical, radiological, and pathological evaluations. Here are some diagnostic tests that can aid in the diagnosis of PEComas:

• Imaging Studies: Imaging modalities such as CT scans, MRI, and ultrasound can help identify the location, size, and characteristics of the tumor [12][14]. These studies can also provide information on the tumor's relationship with surrounding structures.
• Serological Tests: Blood tests may be used to detect specific biomarkers associated with PEComas, such as vascular endothelial growth factor D (VEGF-D) [13].
• Histologic and Cytogenetic Analysis: A definitive diagnosis of PEComa can only be made through histopathological examination of the tumor tissue. This involves analyzing the tumor's cellular morphology, immunohistochemical profile, and cytogenetic features [7][9]. The diagnostic criteria recommended by Folpe in 2005 suggest identifying the malignant PEComa on at least 2 of the following items: tumor size >5 cm, aggressive growth, significant nuclear pleomorphism, and high mitotic activity [6].
• Immunohistochemical Markers: Specific immunohistochemical markers such as CD31 (platelet endothelial cell adhesion molecule-1) can be used to identify blood vessels and vascular tumors, which is a characteristic feature of PEComas [7].

Key Points

• A combination of clinical, radiological, and pathological evaluations is necessary for accurate diagnosis.
• Imaging studies can provide information on the tumor's location, size, and characteristics.
• Serological tests may be used to detect specific biomarkers

Malignant Perivascular Epithelioid Cell Tumors (PEComas): An Overview

Malignant PEComas are a rare and aggressive form of soft-tissue sarcomas, characterized by their association with blood-vessel walls and expression of melanocytic and smooth muscle markers [1]. These tumors are classified as tumors of uncertain malignant potential due to the possibility of recurrences after radical treatment [10].

Treatment Options

Several treatment options have been explored for malignant PEComas. The FDA has approved sirolimus protein-bound particles for this condition, with nab-sirolimus showing activity in patients with malignant PEComa [2]. Additionally, mTOR inhibitors such as sirolimus and everolimus have been effective in treating malignant uterine PEComas, with durable responses observed in some cases [5].

Chemotherapy and Other Therapies

First-line chemotherapy with gemcitabine has been initiated in some cases, although progression of disease was observed after three cycles [6]. Second-line treatment with sirolimus at a dose of 5 mg per square meter of body surface area resulted in stable disease [6]. VEGFR inhibitors and mTOR inhibitors have also

The differential diagnosis for perivascular tumors, also known as PEComas, can be quite broad and depends on various factors such as the location of the mass, histopathological features, and immunohistochemical characteristics.

Possible Differential Diagnoses:

• Leiomyoma and leiomyosarcoma
• Paraganglioma
• Melanoma (primary or metastatic)
• Clear cell sarcoma of soft parts
• Epithelioid smooth muscle tumors
• Hepatic adenomas and hepatocellular carcinoma
• Atypical hemangioma and other uncommon hypervascular neoplasms
• Benign vascular lesions such as vascular malformations
• Malignant melanoma and clear cell sarcoma of tendon and aponeuroses

Key Features for Differential Diagnosis:

• Histopathological features, including the presence of perivascular epithelioid cells, melanocytes, and smooth muscle components
• Immunohistochemical characteristics, such as expression of S-100, CD56, and CD99
• Clinical presentation and location of the tumor

Importance of Accurate Diagnosis:

Accurate diagnosis of PEComas is crucial for determining the appropriate treatment plan and predicting patient outcomes. Misdiagnosis can lead to inappropriate treatment and potentially worsen patient outcomes.

References:

[1] Lai H, Chen C (2023) - Differential diagnosis of PEComa [2] Tirumani SH (2014) - Malignant PEComas: A review of the literature [3] Wannasai K (2023) - Perivascular epithelioid cell tumor of the uterus [4] Flucke U (2020) - Benign vascular lesions as differential diagnosis for PEComa [5] Armah HB (2009) - Malignant melanoma and clear cell sarcoma of tendon and aponeuroses: A review of the literature