Daruwale R*, Kale K**, Waghmare T***, Chauhan AR****.
(* Senior Registrar, ** Assistant Professor, **** Professor, Department of Obstetrics and Gynecology, *** Assistant Professor, Department of Pathology, Seth G.S. Medical College and K.E.M. Hospital, Mumbai, India.)
Angiomyolipomas (AMLs) are benign tumors composed of blood vessels, smooth muscle cells and fat cells. Most commonly found in the kidney, they are also located in the liver and less commonly in the fallopian tubes, ovaries, spermatic cord, palate and colon. They are strongly associated with the genetic disease tuberous sclerosis. Vulval angiomyolipomas are extremely rare and to the best of our knowledge, only one case has been reported in the literature till date.
Angiomyolipomas(AMLs) are benign tumors composed of three main tissue elements, namely mature adipose tissue, thick walled blood vessels, and smooth muscles cells. AMLs are most commonly found in the kidney with an incidence of 0.13%. Few cases of extra renal AML have been reported affecting the liver, retroperitoneum, colon, fallopian tubes, uterus, ovaries, vagina, penis and abdominal wall. We present a rare case report of vulval angiomyolipoma diagnosed on histopathological examination.
A 38 year old female patient para 2, living 2 came with complaint of swelling in the perineal region since 3 months. The swelling was insidious and progressive, and intermittently painful. She had regular menstrual cycles with no menstrual complaints. Per-abdomen examination revealed no abnormality. Local examination of the vulva revealed 5 x 4 cm ovoid swelling on the right side between upper two third and lower one third of labia minora, approximately 2 cm above the fourchette. It was soft in consistency and minimally tender. Per-speculum examination revealed healthy cervix and vagina. On per-vaginal examination, uterus was anteverted, slightly bulky with bilateral fornices free and non tender. All biochemical investigations were within normal limits. Pelvic ultrasound showed a normal sized anteverted uterus with normal endometrial thickness. Bilateral ovaries were normal in size and echotexture and no adnexal pathology was seen. Patient was managed conservatively with antibiotics and analgesics. Pain subsided but due to persistent and uncomfortable swelling, cyst excision was performed. The excised cyst was sent for histopathological examination.
Histopathology report showed non-encapsulated benign neoplasm composed of blood vessels, smooth muscle fibers with interdisposed benign adipose tissue. The blood vessel component showed thin to thick wall, small to medium sized blood vessels. The muscle fibers were arranged encircling the blood vessels forming sheets and at places forming vague fascicles. The fatty tissues component showed clusters of mature adipocytes interspersed in the muscle fibers and vessels. There was no evidence of necrosis, atypical mitosis or malignancy. Immunohistochemistry showed strong diffuse positivity for desmin and smooth muscle actin. The final diagnosis was angiomyolipoma of right side of vulva. Patient was advised CT abdomen and pelvis to look for lesions at other sites; however, she did not comply and was subsequently lost to follow up.
Figure 1.Hematoxylin –eosin stained slide (100X) shows mature adipose tissue intermixed with smooth muscle fibers.
Figure 2.Hematoxylin –eosin stained slide (400 X) shows many thin walled blood vessels with proliferating smooth muscle fibers and adipose tissue. It also shows scanty lymphocytic infiltrate.
Figure 3.Hematoxylin –eosin stained slide (400 X) shows intermixed proliferating blood vessels, smooth muscle fibers and adipose tissue.
Figure 4.Strong and diffuse positivity for desmin and smooth muscle actin on immunohistochemistry.
In 1951, the term “angiomyolipoma” was first used by Morgan to describe a benign renal tumor composed of blood vessels, smooth muscle, and adipose tissue. It has an overall incidence of 0.3-3%. Broadly, there are two types of AMLs: isolated AML and AMLs associated with tuberous sclerosis. Isolated angiomyolipoma occurs sporadically and accounts for 80% of the angiomyolipomas, whereas those associated with tuberous sclerosis are caused by mutations in TSC1 or TSC2 genes (which regulate cell growth and proliferation).[4,5] The mean age at presentation of patients with isolated angiomyolipoma is 40 years. It is about 4 times more common in women than in men. Although most common in the kidney, these tumors have been reported in the liver, retroperitoneum, colon, fallopian tubes, uterus, ovaries, vagina, penis and abdominal wall. A thorough search of literature revealed only one case report of isolated vulval AML.
Angiomyolipomas are generally asymptomatic. Sometimes cases with retroperitoneal AML present with abdominal pain and increasing abdominal girth. Renal and extra renal AMLs can present with complications like degenerative necrosis, hematoma or sudden torrential bleeding due to spontaneous rupture of vessels within, though very rare. Although considered benign, they have an uncertain malignant potential which is an area of active research.
The diagnosis of AML is based on the combination of clinical history, imaging tests, and histological examination. Imaging studies are useful in cases of renal and extra-renal AMLs. On histopathological examination, the gross appearance of tumor is yellow to gray with sizes ranging from few centimeters to upto 20 cm. On microscopic examination, presence of adipocytes, blood vessels and smooth muscle components confirms the diagnosis of AML. The smooth muscle component is mainly comprised of spindle cells and epithelioid cells. In most cases, the tumors stain positive for desmin, muscle specific actin, and HMB45 which helps in accurate diagnosis.HMB45 may be absent in extra renal AML. AML may be confused with lipomatous variant of angiomyofibroblastoma (LAMF). However, on histopathology, these tumors show epithelioid cells in nests, which is not a feature of AML. Also, LAMF stain uniformly positive with vimentin, but only occasionally for desmin and very rarely for smooth muscle actin.[7,8]
Although angiomyolipomas are universally regarded as benign lesions, their malignant potential should not be underestimated. Tumors with features of hemorrhage, necrosis, local invasiveness and high mitotic activity are likely to have poor outcome. Management options for AMLs include conservative management and surgical excision. Surgical excision is considered for tumors that are symptomatic and those with size greater than 4 cm. If opting for conservative management, meticulous follow up is necessary owing to their unknown malignant potential.
Angiomyolipoma though rare, should be considered as one of the differential diagnosis in patients presenting with vulval mass. Usually considered benign, more research is needed to determine their malignant potential.
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Daruwale R, Kale K, Waghmare T, Chauhan AR. Angiomyolipoma Of Vulva. JPGO 2017. Volume 4 No.3. Available from: http://www.jpgo.org/2017/03/angiomyolipoma-of-vulva.html