Dear Editor,
Perivascular epithelioid cell tumours (PEComas) are mesenchymal neoplasms defined by the presence of histologically and immunohistochemically distinctive perivascular epithelioid cells [1]. Perivascular epithelioid cells exhibit myomelanocytic differentiation which are positive for both immunohistochemical markers of melanocyte and smooth muscle cell. The common sites of occurrence include kidney, lung, liver, soft tissues, skin, prostate and bone. PEComa occurring in female genital tract is rare, and the most common site is uterine corpus. Perivascular epithelioid cell tumours occurring in the cervix are extremely rare, and very few cases have been reported till now [2]. We report a case of PEComa of cervix in a 45-year-old postmenopausal woman who presented with a cervical mass.
A 45-year-old multiparous postmenopausal woman presented with history of mass in vagina for 2 months, not associated with pain, bleeding or white discharge per vaginum. Per speculum examination revealed a 4 × 4 cm mass arising from posterior lip of cervix with smooth surface and not bleeding on touch. Excision biopsy of cervical mass was done under IV sedation. Grossly, mass was 4 × 4 × 3 cm in size with tan-coloured cut surface. Histopathological examination showed large round tumour cells with clear cytoplasm and centrally placed round nucleus with spidery appearance arranged in trabecular pattern, cords and around blood vessels (Figs. 1 and 2). There were no mitotic figures, necrosis, nuclear atypia, or infiltrative growth pattern in the sections studied from mass. Immunohistochemical examination showed diffuse and strong positivity of tumour cells for HMB-45 (Human Melan Black-45) and SMA (smooth muscle actin) (Fig. 3). Tumour cells were negative for S100 protein, h-caldesmon and desmin. Diagnosis of PEComa of cervix was made based on the positivity of tumour cells for both melanocytic and smooth muscle cell markers.
Fig. 1.
Microphotograph showing large round tumour cells arranged in thin cords separated by extracellular amorphous material (H&E stain, 40 ×)
Fig. 2.
Microphotograph showing large round tumour cells with clear cytoplasm (glycogenated) with spidery appearance of nucleus (H&E stain, 400 ×)
Fig. 3.
Microphotograph showing diffuse and strong positivity of tumour cells for HMB 45 immnunohistochemical marker (IHC-HMB-45, 40 ×)
The differential diagnosis of clear cell tumours of cervix includes clear cell adenocarcinoma, a clear cell variant of squamous cell carcinoma, clear cell adenosquamous carcinoma, PEComas, metastatic malignant melanoma, clear cell sarcoma and epithelioid variant of leiomyosarcoma [3, 4]. Clinical profile, pattern of arrangement of tumour cells, nuclear features, association with Human Papilloma virus and unique immunohistochemical markers help to differentiate these lesions.
PEComas are considered to be malignant with capacity to metastasize when they are more than 5 cm in size with necrosis, high nuclear grade, infiltrative growth pattern and > 1 mitotic figure/50 HPF as per Folpes criteria. In our case, there were no features suggestive of malignancy [5]. Malignant PEComa mimics melanoma and leiomyosarcoma in histopathological examination, and immunohistochemistry helps in differentiating these lesions. PEComas are positive for HMB45, Melan A markers like malignant melanoma, but are negative for S100 protein expression in contrast to malignant melanoma. Leiomyosarcoma and PEComas are positive for SMA, but negativity of PEComas for h-caldesmon differentiates it from leiomyosarcoma. A case of benign PEComa of cervix misdiagnosed as malignant melanoma and patient underwent radical surgery and radiotherapy has been reported. This underscores the importance of complete immunohistochemical evaluation for diagnosing PEComa [6]. Clinicians and pathologists should have high degree of suspicion to diagnose this rare tumour.
Author Contribution
VS and PB managed the case. PB, ABT, and VS did literature search and drafted the manuscript.
The manuscript has been read and approved by all the authors, the requirements for authorship as stated earlier in this document have been met, and each author believes that the manuscript represents honest work, and the information is not provided in another form.
Declarations
Conflict of Interest
The authors declare no competing interests.
Footnotes
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Contributor Information
Vijayan Sharmila, Email: sharu_jipmer@yahoo.co.in.
Padmapriya Balakrishnan, Email: sudhadevi.balakrishnan@gmail.com.
Thirunavukkarasu Arun Babu, Email: babuarun@yahoo.com.
References
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