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Year : 2015  |  Volume : 58  |  Issue : 2  |  Page : 226-228
Angiomyomatous hamartoma in an inguinal lymph node with proliferating pericytes/smooth muscle cells, plexiform vessel tangles, and ectopic calcification

1 Department of Pathology, Taipei Medical University, Taipei, Taiwan
2 Department of Surgery, Division of General Surgery, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan
3 Department of Radiology, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan

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Date of Web Publication17-Apr-2015


Angiomyomatous hamartoma (AMH) is a rare benign lesion, which occurs almost exclusively in the inguinal lymph nodes. We herein report a case of a female elder who presented with a long-standing inguinal mass. Microscopically, the mass showed a zonal distribution, characterized by thick-walled muscular vessels, fibrosis, and calcification in the hilum and proliferating spindle cells around thin-walled vessels and plexiform vessel tangles at the periphery. The spindle cells show positive immunoreactivity of smooth muscle actin and CD34 with a heterogeneous expression of desmin and CD44. Although the pathogenesis of AMH remains uncertain, the histological features and immunohistochemical findings of this case imply a disordered or exuberant angiogenic process.

Keywords: Angiomyomatous hamartoma, ectopic calcification, inguinal lymph node, pericyte, plexiform vessel

How to cite this article:
Lee CH, Chang TC, Ku JW. Angiomyomatous hamartoma in an inguinal lymph node with proliferating pericytes/smooth muscle cells, plexiform vessel tangles, and ectopic calcification. Indian J Pathol Microbiol 2015;58:226-8

How to cite this URL:
Lee CH, Chang TC, Ku JW. Angiomyomatous hamartoma in an inguinal lymph node with proliferating pericytes/smooth muscle cells, plexiform vessel tangles, and ectopic calcification. Indian J Pathol Microbiol [serial online] 2015 [cited 2022 Jul 7];58:226-8. Available from: https://www.ijpmonline.org/text.asp?2015/58/2/226/155325

   Introduction Top

Angiomyomatous hamartoma (AMH), first described by Chan et al., [1] is rare and occurs almost exclusively in the inguinal lymph nodes. It tends to affect young to middle-aged male with a peak incidence in the sixth decade of life. Patients typically have a long-standing mass or, in some cases, suffer from lymphedema or swelling of the ipsilateral leg. [1],[2] Light microscopy reveals a proliferation of smooth muscle cells and fibrous tissue with thick-walled muscular vessels in the hilum. [1] Simple excision is curative. [1] Only 29 cases of AMH have been reported, and we herein report an 89-year-old female presenting with inguinal lymphadenopathy.

   Case Report Top

An 89-year-old female presented with a right inguinal mass, which had been noticed for about 40 years and seemed to be getting bigger in the last half year. The patient had a long history of hypertensive heart disease, and she had a total hysterectomy for uterine myoma >40 years ago. Routine laboratory results were unremarkable. Computerized tomography revealed an enlarged right inguinal lymph node with a rim-like enhancement [Figure 1].
Figure 1: Coronal computerized tomography scan of angiomyomatous hamartoma. An enlarged right inguinal lymph node with a rim-like enhancement at the periphery

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The lymph node measured 5 cm × 3 cm × 1 cm and appeared firm and white. Microscopically, the nodal parenchyma was largely replaced by haphazardly arranged spindle cells, leaving a rim of residual lymphoid tissue at the periphery [Figure 2]a. A mixture of thin and thick-walled vessels were present in the background, and the spindle cells blended imperceptibly into the vascular walls. The thick-walled vessels were limited to the hilum, with a few distorted, plexiform vessel tangles around [Figure 2]b. Scattered mature adipocytes and ectatic lymphatics were present [Figure 2]c. Focal sclerosis and calcification with minimal spindle cell proliferation were also seen in the hilum [Figure 2]d. Immunohistochemical studies revealed a zonal distribution of the spindle cells and vessels [Figure 3]. The spindle cells were CD34-positive, smooth muscle actin (SMA)-positive and CD31-negative [Figure 3]a and b, and they tended to express desmin when approaching the convex surface of the lymph node [Figure 3]c. There were also some CD44-positive and SMA-positive spindle cells around the thin-walled vessels near the hilum [Figure 3]d. The thin-walled vessels were relatively evenly distributed [Figure 3]b. In contrast, the thick-walled vessels were limited to the hilum [Figure 3]c. Immunostaining for HMB-45 was negative.
Figure 2: Microscopic features of angiomyomatous hamartoma. (a) Nodal parenchyma replaced by spindle cells with a residue at periphery. (b) Spindle cells blended into a plexform vessel (left upper). (c) Adipocytes and lymphatics (asterisk). (d) Focal sclerosis with calcification in hilum

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Figure 3: Immunohistochemistry of angiomyomatous hamartoma. (a) Spindle cells positive for CD34. (b) Thin-walled vessels evenly distributed (CD31). (c) Thick-walled vessels limited to the hilum (left), and spindle cells away from the hilum expressed the desmin. (d) CD44-positive pericytes/smooth muscle cells around thin-walled vessels (insert, CD31)

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The patient is doing well 15 months after simple excision.

   Discussion Top

Based on the histological features, AMH is considered as an acquired hamartomatous lesion of the lymph nodes, characterized by a disorganized proliferation of blood vessels, smooth muscle cells, and fibrous tissue. [1] Fat components and peculiar patterns of vascular proliferation are occasionally seen. [3],[4] Immunohistochemistry suggests a smooth muscle differentiation, showing positive reactivity for actin, desmin and h-caldesmon and negative for CD31 and HMB-45. [1],[3],[4]

Although the pathogenesis of AMH remains uncertain, the disease process appears to start in the hilum then extend to the convex surface of the node. [1] A similar smooth muscle proliferation of vascular origin in the nodal hilum, which affects the inguinal and axillary lymph nodes with a male predominance and a tendency to involve >1 regional nodes, has been reported as an incidental finding, and a hypothesis of a reparative angiogenic response to locally acting agents was proposed. [5] Given that lymphedema associated with some cases of AMH may or may not regress after tumor excision, obstruction or impairment of the lymphatic flow could contribute to the pathogenesis of AMH. [2],[6]

Dargent et al. proposed a "disordered angiogenesis" hypothesis based on the observation of proliferating pericytes/smooth muscle cells around plexiform or glomeruloid vessels in their case, which is similar to those described in primary pulmonary hypertension as well as in some experimental studies on angiogenic response-induced by vascular permeability factor/vascular endothelial growth factor-A (VEGF-A). [4],[7],[8] In animal models, the initial response to VEGF-A is characterized by detachment of pericytes from preexisting microvessels, which may evolve into smaller daughter vessels, disorganized vessel tangles, and medium-sized muscular vessels. [8] Detached pericytes may differentiate into fibroblast-like cells, contribute to fibrosis and play a role in ectopic calcification. [9]

In our case, a zonal distribution of spindle cells and vessels could represent the sequence of endothelial-pericyte interactions in angiogenesis. Toward the convex surface of lymph node, there were proliferating spindle cells around thin-walled vessels and plexiform vessel tangles. In contrast, thick-walled muscular vessels fibrosis, and calcification were present in the hilum with minimal spindle cell proliferation. In addition, the spindle cells show positive immunoreactivity for SMA and CD34 and a heterogeneous expression of desmin and CD44 in a zonal distribution, suggesting a pericyte/smooth muscle cell differentiation and/or maturation. It is also worth noting that calcification in lymph nodes outside the thoracic cage is rare, and it is typically associated with malignancy, infection or other inflammatory diseases. [10] Our case was free of all the aforementioned situations, and ectopic calcification initiated by the pericytes in angiogenesis may be the reason.

Angiomyomatous hamartoma should be differentiated from angiomyolipoma, which is a hamartomatous proliferation of smooth muscle cells, thick-walled vessels, and adipocytes, and it may mimic AMH with a fat component. However, angiomyolipoma typically involves the kidney and rarely the retroperitoneal lymph nodes, and the tumor cells usually show an epithelioid appearance, hypercellularity, pleomorphism and positive immunoreactivity for HMB-45. [3] Another hamartomatous lesion of the lymph node is lymphangiomyoma, which is characterized by proliferation of smooth muscle cells around anastomosing ectatic vascular spaces. It affects exclusively in women of child-bearing age and tends to occur in the thoracic and intra-abdominal lymph nodes. In contrast to AMH, the tumor cells of lymphangiomyoma are plumper, light-staining and reactive for HMB-45. [1],[3]

   Conclusion Top

We depict detailed histological features of a case of AMH of the lymph node. A zonal distribution of proliferating pericytes/smooth muscle cells and vessels, as well as the presence of plexiform vessel tangles, ectopic calcification, and the immunoprofiling of the pericytes/smooth muscle cells, imply disordered or exuberant angiogenesis in the pathogenesis.

   References Top

Chan JK, Frizzera G, Fletcher CD, Rosai J. Primary vascular tumors of lymph nodes other than Kaposi's sarcoma. Analysis of 39 cases and delineation of two new entities. Am J Surg Pathol 1992;16:335-50.  Back to cited text no. 1
Bourgeois P, Dargent JL, Larsimont D, Munck D, Sales F, Boels M, et al. Lymphoscintigraphy in angiomyomatous hamartomas and primary lower limb lymphedema. Clin Nucl Med 2009;34:405-9.  Back to cited text no. 2
Ram M, Alsanjari N, Ansari N. Angiomyomatous hamartoma: A rare case report with review of the literature. Rare Tumors 2009;1:e25.  Back to cited text no. 3
Dargent JL, Lespagnard L, Verdebout JM, Bourgeois P, Munck D. Glomeruloid microvascular proliferation in angiomyomatous hamartoma of the lymph node. Virchows Arch 2004;445:320-2.  Back to cited text no. 4
Channer JL, Davies JD. Smooth muscle proliferation in the hilum of superficial lymph nodes. Virchows Arch A Pathol Anat Histopathol 1985;406:261-70.  Back to cited text no. 5
Mauro CS, McGough RL 3 rd , Rao UN. Angiomyomatous hamartoma of a popliteal lymph node: An unusual cause of posterior knee pain. Ann Diagn Pathol 2008;12:372-4.  Back to cited text no. 6
Ohta-Ogo K, Hao H, Ishibashi-Ueda H, Hirota S, Nakamura K, Ohe T, et al. CD44 expression in plexiform lesions of idiopathic pulmonary arterial hypertension. Pathol Int 2012;62:219-25.  Back to cited text no. 7
Dvorak HF, Weaver VM, Tlsty TD, Bergers G. Tumor microenvironment and progression. J Surg Oncol 2011;103:468-74.  Back to cited text no. 8
Ronchetti I, Boraldi F, Annovi G, Cianciulli P, Quaglino D. Fibroblast involvement in soft connective tissue calcification. Front Genet 2013;4:22.  Back to cited text no. 9
Grotenhuis BA, Wijnhoven BP, Hermans JJ, Biermann K, van Lanschot JJ. Fixed size of enlarged calcified lymph nodes in esophageal adenocarcinoma despite complete remission. Case Rep Gastroenterol 2009;3:182-86.  Back to cited text no. 10

Correspondence Address:
Dr. Chii-Hong Lee
Department of Pathology, Shuang Ho Hospital, Taipei Medical University, 291, Zhongzheng Road, Zhonghe District, New Taipei City 23561
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.155325

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  [Figure 1], [Figure 2], [Figure 3]

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