Letter to the Editor

A case of intravenous lobular capillary hemangioma ofthe renal vein mimicking renal cell carcinomapin_2821 441..443

To the Editor:Lobular capillary hemangioma (LCH), also known as pyo-genic granuloma, is a benign hypervascular tumor thatusually affects the skin and mucous membranes of the headand neck region.1,2 In rare instances, an intravenous coun-terpart of LCH occurs, in which capillary proliferation is con-fined primarily to the venous lumen. This unusual variant ofLCH, intravenous lobular capillary hemangioma (IVLCH),was first documented as a series of 18 cases of intravenouspyogenic granulomas by Cooper et al. in 1979.3 Most casesinvolve the head and neck region, followed by the upperextremities. An unusual case of IVLCH of the renal vein thatmimicked renal cell carcinoma invading into the inferior venacava is reported here.

A 36-year-old Japanese woman presented with a 2-monthhistory of epigastric pain and went to a local hospital.Abdominal computed tomography (CT) and magnetic reso-nance imaging (MRI) revealed a left renal mass invading intothe left renal vein with extension to the inferior vena cava.The radiological diagnosis was renal cell carcinoma, and thepatient was referred to our hospital for surgery. She had nohistory of surgery or trauma to the abdomen, and her medicalhistory was unremarkable. Physical examination revealed nosignificant findings. Her blood tests were within normal limits,and urinalyses were negative. CT imaging of the abdomenshowed a large mass in the left renal vein with a heteroge-neously enhancing effect (Fig. 1a). Serial images revealedan irregular mass in the upper part of the left kidney, whichhad continuity with the intravascular tumor (Fig. 1b). Nometastatic lesions were noted in the lymph nodes and otherorgans. Collateral veins could not be detected. The preop-erative diagnosis was advanced renal cell carcinoma withvenous invasion, and a left radical nephrectomy was per-formed. The resected specimen was submitted for histo-pathological evaluation.

The kidney was 10 ¥ 5.1 ¥ 4.6 cm in size, and the cut surfaceshowed a solid, well demarcated, and pale brown mass mea-suring 8.5 ¥ 7.5 cm in its maximal dimensions. The lesionoccluded the left renal vein and extended continuously into theinferior vena cava (Fig. 1c). Macroscopically, no apparentinvasion into the renal parenchyma could be detected. Micro-scopically, most of the tumor was confined within the vein(Fig. 2a), with partial attachment to the vascular wall by afibrovascular stalk. Local spreading into the renal paren-chyma was occasionally observed without capsule formation

(Fig. 2b). The tumor consisted of lobular proliferation of thesmall sized capillary vessels separated by loose myxoid andedematous stroma (Fig. 2c). In some parts of the tumor, asinusoid-like pattern of capillary proliferation was noted.Under a higher magnification, the endothelial cells of thecapillaries were flattened and lacked both marked nuclearatypia and mitotic figures, although a slight degree of nuclearenlargement was noted (Fig. 2d). Degenerative changes suchas infarction, interstitial sclerosis, and vascular thrombi werenot observed. Immunohistochemical studies were performedwith automated immunostainers (Benchmark-XT, Roche,Tokyo, Japan) using the following antibodies: anti-CD34 (NU-4A1, 1:4 dilution, Nichirei, Tokyo, Japan), anti-CD10 (56C6,1:1 dilution, Leica, Tokyo, Japan), and anti-PAX8 (BC12, 1:1dilution, Biocare Medical, Concord, CA, USA). Antigenretrieval was performed by autoclaving in EDTA buffer atpH 8.5 or 9.0 for 90 min (CD34, CD10) and 20 min (PAX8). Onimmunohistochemical examination, only the endothelial cellswere strongly positive for CD34 (Fig. 2d inset). Immunostain-ing for CD10 and PAX8 was totally negative (not shown). Fromthese findings, the final pathological diagnosis was IVLCH ofthe renal vein. The patient has had a good course with nopostoperative complications and has been followed for4 months after surgery without any evidence of recurrence.

Intravenous lobular capillary hemangioma is a rare benignvascular tumor, and 44 cases have been reported since thefirst case in 1979. While most cases of IVLCH occur in thevascular lumen of the head and neck region, two singlecases of IVLCH involving a solid organ have been reported;one in the kidney and one in the ovary.4,5 The tumor was anincidental finding within the serous cystadenoma in the casereported by McKee et al.,5 whereas an apparent mass lesionwas radiologically detected in the other case.4 Grossly, mostlesions appear as polypoid, rubbery, vascular nodules thatare attached to the venous wall by a fibrovascular stalk.Histologically, the lesion is composed of a lobular arrange-ment of multiple capillaries lined by a flattened endotheliallayer. These capillary buds are surrounded by edematousstroma containing small arteries, veins, and collagenousfibers.

Montgomery et al.6 recently reported six cases of anasto-mosing hemangioma of the genitourinary tract, and additionalcases were later described by Kryvenko et al.7 Anastomosinghemangioma is characterized by a sinusoidal-like pattern oftightly packed capillary channels that occasionally resemblesplenic parenchyma. An intravascular growth pattern hasalso been reported. In the present case, a sinusoidal patternof capillary proliferation was observed, raising the possibility

Pathology International 2012; 62: 441–443 doi:10.1111/j.1440-1827.2012.02821.x

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© 2012 The AuthorsPathology International © 2012 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd

that anastomosing hemangioma could be the critical differ-ential diagnosis. Recently, Brown et al.8 reported ‘anasto-mosing’ architecture in 5 of 14 cases of renal capillaryhemangioma, indicating that renal hemangioma could showa unique spleen-like morphology. Although we cannot denythe possibility that the present case could be categorized asan anastomosing hemangioma, we stress the highly intra-vascular nature that was not mentioned in the describedcases of anastomosing hemangioma, and we consider that

the current case was IVLCH. Due to the scarcity of reportedcases, the pathological profile of anastomosing hemangiomaof the kidney has not been fully established, and furtherstudies will be needed to set strict diagnostic criteria.

IVLCH can be described as a heterogeneously enhancinglesion on contrast-enhanced CT imaging as reported byPradhan et al.9 Another report by Winn et al.10 described acase of intravenous pyogenic granuloma of an angular veinthat showed a mildly heterogenic, contrast-enhancing lesion.

Figure 1 (a) Contrast-enhanced CTimaging shows a mass lesion in the leftrenal vein with a heterogeneously enhanc-ing effect, measuring 9.5 ¥ 3.3 cm (arrowheads). (b) In the upper part of the leftkidney, an irregular mass lesion (arrowheads) is detected. (c) Gross appearanceof a representative cut section. A well-demarcated mass occludes the left renalvein (white arrow heads) and extends intothe inferior vena cava (arrows). Peripheralsmaller veins are also occupied by thetumor (open arrow heads).

Figure 2 Microscopic findings of therenal tumor. (a) At scanning magnification,the tumor is confined within the bloodvessels. The arrow indicates anothersmall focus of intravascular tumor. (b)Occasionally, tumor growth (left part ofthe image) can be found within therenal parenchyma. (c) Lower magnifica-tion shows lobular proliferation of the cap-illary vessels separated by loose myxoidand edematous stroma. (d) High-powermagnification shows flattened endothelialcells without apparent nuclear atypia.Inset shows CD34 immunostaining.

442 Letter to the Editor

© 2012 The AuthorsPathology International © 2012 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd

These results reflect the tightly packed lobular capillarynetworks that comprise the lesion. The present case alsodemonstrated a heterogeneous enhancing effect oncontrast-enhanced CT, which is in accordance with theprevious reports of IVLCH.

The present case demonstrates the diagnostic challengeof renal IVLCH, because intravenous spreading and tumorinvasion into the inferior vena cava can be occasionally seenin clear cell renal cell carcinoma (CCRCC). Histologically,CCRCC frequently shows a network of small blood vesselswith a very delicate and uniformly small caliber, which is theshared feature with capillary hemangioma. While the exten-sive intravascular growth pattern is reminiscent of CCRCC,the absence of a gross mass lesion within the renal paren-chyma, the pale brown color of the tumor, and the lack ofhistological findings of CCRCC despite tissue processing ofthe entire lesion led us to consider the possibility of IVLCH. Inaddition, immunohistochemical studies using anti-CD10 andanti-PAX8 antibodies showed no positive staining within thetumor, which argues against CCRCC.

In summary, an unusual case of IVLCH of the renal veinwas described. The present case highlights that IVLCH couldbe large enough to occupy the renal vein and inferior venacava, and also indicates that IVLCH can be an importantmimicker of CCRCC. Awareness of this rare site of IVLCHshould increase its appropriate recognition and allow eluci-dation of its clinicopathological profile.

ACKNOWLEDGMENTS

The authors thank Dr. Yoji Nagashima (Department ofMolecular Pathology, Yokohama City University Schoolof Medicine) and Dr. Masaharu Fukunaga (Department of

Pathology, Jikei University School of Medicine) for their majorcontribution to the pathological diagnosis.

Mai Takeuchi, Shigeo Hara and Tomoo ItohDivision of Diagnostic Pathology, Department ofPathology, Kobe University Graduate School of

Medicine, Chuo-ku, Kobe, Japan

REFERENCES

1 Mills SE, Cooper PH, Fechner RE. Lobular capillary heman-gioma: The underlying lesion of pyogenic granuloma. A study of73 cases from the oral and nasal mucous membranes. Am JSurg Pathol 1980; 4: 470–79.

2 Jafarzadeh H, Sanatkhani M, Mohtasham N. Oral pyogenicgranuloma: A review. J Oral Sci 2006; 48: 167–75.

3 Cooper PH, McAllister HA, Helwig EB. Intravenous pyogenicgranuloma. Am J Surg Pathol 1979; 3: 221–8.

4 Hull GW, Genega EM, Sogani PC. Intravascular capillaryhemangioma presenting as a solid renal mass. J Urol 1999;162: 784–5.

5 McKee GT, Fletcher CDM, McKee PH. Visceral intravascularcapillary hemangioma. Arch Pathol Lab Med 1987; 111: 390–92.

6 Montgomery E, Epstein JI. Anastomosing hemangioma of thegenitourinary tract, a lesion mimicking angiosarcoma. Am JSurg Pathol 2009; 33: 1364–9.

7 Kryvenko ON, Gupta N, Meier FA et al. Anastomosing heman-gioma of the genitourinary system. Am J Clin Pathol 2011; 136:450–57.

8 Brown JG, Folpe AL, Amin MB et al. Primary vascular tumorsand tumor-like lesions of the kidney: A clinicopathologic analysisof 25 cases. Am J Surg Pathol 2010; 34: 942–9.

9 Pradhan S, Bazan H, Salem R et al. Intravenous lobular capil-lary hemangioma originating in the iliac veins: A case report. JVasc Surg 2008; 47: 1346–9.

10 Winn BJ, Herreid PA, Sires BS. Intravenous pyogenic granu-loma of the angular vein. Opthal Plast Reconstr Surg 2009; 25:341–3.

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© 2012 The AuthorsPathology International © 2012 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd