|Year : 2013 | Volume
| Issue : 2 | Page : 305-307
Pigmented perivascular epithelioid cell tumor of the liver: Report of a rare case with brief review of literature
Susama Patra1, Mukul Vij1, Venugopal Kota2, Ravindranath Kancherla3, Mohamed Rela2
1 Department of Pathology, Global Hospital and Health City, Chennai, Tamil Nadu, India
2 Department of Liver Transplantation and Hepatobiliary Surgery, Global Hospital and Health City, Chennai, Tamil Nadu, India
3 Department of Surgical Gastroenterology, Global Hospital and Health City, Chennai, Tamil Nadu, India
|Date of Web Publication||13-Jun-2013|
Department of Pathology, Global Hospital and Health City, Chennai - 600 100, Tamil Nadu
Source of Support: Nuclear Science and Technology Research Institute (NSTRI), Conflict of Interest: None
The perivascular epithelioid cell tumor (PEComa) family of tumors includes angiomyolipoma, lymphangioleiomyomatosis, clear cell sugar tumor of the lung, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, and rare clear cell tumors of other anatomical sites (PEComas-NOS). Among the PEComas-NOS, pigmented variants are extremely rare. The case concerns a 50-year-old female who presented with pain in right hypochondrium. The resected specimen included a 24 × 18 × 9 cm mass. The tumor was histologically characterized by both spindle and epithelioid cells with round to oval nuclei and clear to eosinophilic cytoplasm containing abundant melanin pigment. The stroma demonstrated intervening, thin, fibrovascular septa. Immunohistochemically, the tumor cells were strongly positive for HMB-45, weak positive for smooth muscle actin (SMA), and negative for Hep Par 1, Glypican 3, MUM-1, and S-100 protein. The patient had no evidence of disease 24 months after surgery. Pathologists and clinicians should know about the existence of pigmented perivascular epithelioid cell tumor of the liver.
Keywords: Liver, melanin pigment, perivascular epithelioid cell tumor
|How to cite this article:|
Patra S, Vij M, Kota V, Kancherla R, Rela M. Pigmented perivascular epithelioid cell tumor of the liver: Report of a rare case with brief review of literature. J Can Res Ther 2013;9:305-7
|How to cite this URL:|
Patra S, Vij M, Kota V, Kancherla R, Rela M. Pigmented perivascular epithelioid cell tumor of the liver: Report of a rare case with brief review of literature. J Can Res Ther [serial online] 2013 [cited 2019 Sep 20];9:305-7. Available from: http://www.cancerjournal.net/text.asp?2013/9/2/305/113401
| > Introduction|| |
Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells (PECs). , The PEComa family of tumors includes angiomyolipoma (AML), lymphangioleiomyomatosis ( (LAM), clear cell sugar tumor of the lung (CCST), clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, and rare clear cell tumors of other anatomical sites, such as the liver, uterus, vulva, rectum, urinary bladder, abdominal wall, and pancreas (PEComas-NOS). Only 12 cases of PEComa-NOS of liver have been reported. ,,,, Among the PEComas-NOS, pigmented variant is extremely rare and has been reported occasionally in kidney, uterus, and pelvis. , To the best of the author's knowledge, this is the first case report of pigmented PEComa-NOS of the liver.
| > Case Report|| |
The present case concerns a 50-year-old female who presented to us with pain in right hypochondrium associated with intermittent vomiting and loss of appetite since 1 year. On examination, there was mild nontender hepatomegaly. The computed tomography scan of the liver revealed a multiple hemangiomas in both the lobes of the liver, the largest measuring 15 × 12 cm in segments 5 and 6 and 10 × 10 cm lesion in segment 8 [Figure 1]a. Her liver function tests showed elevated bilirubin (4.5 mg/dl). Her serum glutamate oxaloacetate transaminase (SGOT; 5631 IU/l) and serum glutamate pyruvate transaminase (SGPT; 1931 IU/l) were elevated, while gamma-glutamyl transpeptidase (GGT; 46 IU/l) was normal. Her alkaline phosphatase was 611 IU/l. She was noncirrhotic with normal alpha-fetoprotein (AFP; 1.2ng/ml). In view of the symptomatic space occupying lesionin the liver, she was taken up for surgery. We received the resected specimen measuring 24 × 18 × 9 cm with a rim of normal liver. The external surface of the mass was smooth, gray brown in color with multiple congested blood vessels. Cut sections through the mass showed solid and tiny cystic areas. It was circumscribed and also showed few brownish black areas [Figure 1]b. The authors took 17 sections from different parts of the tumor and 3 sections from the adjacent liver.
|Figure 1: (a) CT scan showing a large tumor; (b) gross specimen; (c) circumscribed tumor; (d) perivascular tumor cells; (e) epithelioid tumor cell; (f) congested cystic spaces in the tumor|
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Routine hematoxylin-eosin-stained sections from formalin-fixed, paraffin-embedded tissue were examined. Histologically, the tumor was unencapsulated and circumscribed [Figure 1]c and composed of both spindle and epithelioid cell types arranged in solid sheets, nests, and vague fascicles invested with thin-walled vascular channels. The tumor frequently showed dilated vascular channels with radial arrangement of tumor cells [Figure 1]d. The cells showed abundant cytoplasm that varied from clear to eosinophilic [Figure 1]e. The nuclei were round to oval and plump with dispersed to vesicular chromatin and conspicuous to prominent eosinophilic nuclei. Focal nuclear pleomorphism was observed. There were cystic areas containing red blood cells [Figure 1]f. No necrosis or venous invasion was present. No adipocyte, smooth muscle, or thick-walled, torturous vessels were present. Multiple foci showed intracellular deposits of brown pigments within the spindle and epithelioid cells [Figure 2]a. The Mason Fontana stained the brown pigments black, confirming it as melanin [Figure 2]b. The pigment was bleached by melanin bleach [Figure 2]c. Periodic acid Schiff staining with diastase confirmed the presence of abundant glycogen in tumor cells [Figure 2]d. Immunohistochemistry showed diffuse and strong positivity of the tumor cells with HBM-45 [Figure 2]e and focal positivity for smooth muscle actin (SMA) [Figure 2]f. Heppar-1, Glypican 3, pancytokeratin, desmin, MUM-1, and S-100 were negative. The postoperative stay of the patient was uneventful with good recovery and she was discharged on the 23 rd postoperative day. Twenty-four months after surgery, the patient remains in good health with no evidence of local recurrence or metastasis.
|Figure 2: (a) Tumor cell containing pigment; (b) Masson Fontana stain; (c) melanin bleach; (d) PAS stain displaying glycogen content; (e) diffuse HMB-45 immunopositivity of the tumor cells; (f) focal SMA immunopositivity|
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| > Discussion|| |
The World Health Organization defines PEComas as mesenchymal tumors composed of histologically and immunohistochemically distinctive PECs.  The group comprising solely PECs are rare, morphologically and immunophenotypically similar tumors arising at a variety of visceral (commonly gastrointestinal, gynecologic, and genitourinary) and soft tissue (commonly retroperitoneal, abdominopelvic, and cutaneous) sites and has been collectively termed non-AML, non-LAM, non-CCST PEComas; or PEComas other than AML, LAM, or CCST; or PEComas-not otherwise specified (PEComas-NOS). PEComas-NOS in the liver, not related to the falciform ligament, are relatively uncommon. The tumor is more common in females, with a broad age range. In a few cases, the condition has been associated with the tuberous sclerosis complex. We identified 12 cases of hepatic PEComa-NOS, composed solely of PECs, that were reported in the English literature. ,,,, These 12 cases arose in 10 women and 2 men, with a mean patient age of 47 years (range 25-70 years). All cases were positive for melanocytic and myogenic markers. None of the cases contained melanin pigment. The present case was of a 50- year-old female with lesion in the liver.
For a definite diagnoses of PEComa, histological findings and immunohistochemical conformation are essential. ,, PEComa cells are characterized by their perivascular location, often with radial arrangement around the vascular lumen. Typically, tumor cells are epithelioid and spindle-shaped and have abundant clear to pale eosinophilic granular cytoplasm. The most important finding is positive immunostaining with both melanocytic [HMB-45 and/or melan-A (not performed in present case)] and smooth muscle (actin and/or desmin) markers. ,, In the present case, those histological findings, especially positive staining with both HMB-45 and SMA, were critical for the final diagnosis. Few cases are reported with prominent nucleoli as seen in our case. The tumor cells also contained abundant glycogen as reported in the literature. The microscopic appearances of angiomyolipoma are extensively varied, so thorough sampling is required to rule out the presence of smooth muscle, fat, and thick-walled blood vessels, before making the diagnosis of PEComa-NOS. In the present case, tumor was composed solely of PECs. The presence of pigment in PEComa-NOS is extremely rare. Only few reported PEComas in kidney, pelvis, and uterus have been observed to contain melanin pigment and in these cases differential diagnosis of malignant melanoma should also be considered. , However, the possibility of metastatic malignant melanoma in the present case was very remote. Although primary skin melanoma occasionally regresses spontaneously, the patient had no history or clinical manifestation of cutaneous melanoma. There was no history of mass per rectum, rectal bleeding, tenesmus, pain, and/or change in bowel habits in the present case to rule our anal or colorectal melanoma. There was no history of any eye symptoms in the present case to rule out the possibility of metastatic ocular melanoma. Metastatic lesions are usually multiple. Metastatic melanomas grow rapidly and usually lead to fatal outcome in less than 6 months. The restriction of the tumor to the parenchyma, its organized pattern, its fine vascular channels, and the negative result of S-100 and MUM-1 proteins in the present case made the diagnosis of malignant melanoma very unlikely.
The vast majority of the reported PEComas seems to behave in a benign fashion, although the malignant course of these tumors with local recurrences and distant metastases has been also reported. A high mitotic activity (>1 per 50 high-power fields), atypical mitotic figures, coagulative tumor cell necrosis, marked nuclear pleomorphism and atypia, hypercellularity, infiltrative type of growth pattern, and large tumor size (>70 mm) are features potentially related to malignancy. ,, The present case was potentially malignant. However, the definite criteria of malignancy in PEComa have not yet been formally established. For this reason, a long-term periodic follow-up is reasonable in every case of PEComa-NOS.
| > Conclusion|| |
of liver is a rare entity. Despite considerable advances in recognition of these unusual lesions, the origin of (or line of differentiation) the PEC (and their tumor) remains elusive and additional cases with longer clinical follow-up must be evaluated before we can accurately predict the behavior of these distinctive tumors.
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[Figure 1], [Figure 2]