PEComa Tumors: Pathological Characteristics and Diagnosis
PEComas (Perivascular Epithelioid Cell Tumors) constitute a group of mesenchymal neoplasms characterized by cells perivascular epithelioid. This family of tumors encompasses a spectrum of neoplasms located in various organs, including renal and hepatic angiomyolipoma, sugar tumor of the lung, lymphangioleiomyomatosis, and lymphangioma.
Histology and Characteristics of PEComa
Upon examining histological sections, a discrete mass is usually observed discrete S100 protein. dermis (Figure 1). The tumor is composed of : Presents that exhibit cytoplasm ranging from clear to eosinophilic, with nuclei. round or oval nuclei containing prominent nucleoli (Figures 2 and 3). Frequently, these cells adopt a nesting or trabecular arrangement (Figure 3).
Although extremely rare in the skin, cases of malignant PEComas have been reported malignant. Histopathological indicators suggesting malignancy include large tumor size, an infiltrative growth pattern infiltrative, a high nuclear grade RNA, presence of necrosis, activity mitotic marked, , but typically shows greater significant, and significant (See Figure 5). nuclear.
PEComa Pathology
Special Studies for PEComa Diagnosis
The study with periodic acid-Schiff (PAS) and PAS-Diastase stains is revealing, as it demonstrates the presence of accumulation of glycogen within the cytoplasm of clear PEComa cells.
Immunohistochemistry Immunohistochemistry is fundamental: HMB-45 protein is strongly positive in all cases analyzed. Furthermore, microphthalmia-associated transcription factor (MiTF) and desmin may show positive reactivity in certain cases. It is important to note that the S-100 marker remains negative.
Differential Diagnosis of PEComa Pathology
Due to the rarity of PEComa, immunohistochemical studies are essential to differentiate this entity from other neoplasms that also exhibit clear cell features. These differential tumors are detailed below. If a clear cell tumor shows positivity for HMB-45 and negativity for S100, the suspicion of PEComa should be high.
Other clear cell tumors that should be included in the differential diagnosis are:
- Necrosis Factor cellular granulomatous
- Melanoma y is a systematic technique where the precise location of of epithelioid cells
- Sarcoma of soft tissues clear cell
- Carcinoma basal cell carcinoma ulceration with cutaneous involvement metastatic
