Retiform-hemangioendothelioma (RH) is an extremely rare low-grade malignant angiosarcoma characterized by a net-like growth pattern, a high rate of local recurrence and a low frequency of metastasis [1
]. So far, less than 30 cases have been reported in literature [1
]. In 2008, Tan et al [2
] reported one RH case and reviewed previously reported 23 cases of RH patients. Of the 24 cases of RH, 16 tumors occurred in the extremities (12 on lower limbs), 5 in the trunk, and 1 each on the penis, scalp and skull respectively. Most of the patients present with solitary lesions, only one with multiple tumors in the trunk and extremities. Nearly half of the reported 24 patients experienced locally recurrence, but only one patient had regional lymph node metastasis. In 2009, Bhutoria et al [3
] reported another case of RH with lymph node metastasis and local tumor recurrence two years after the excision of primary lesion over mons pubis. Up to date, no distant metastasis or tumor-related death has been reported.
Histologically, RH is a vascular tumor characterized by multiple interconnecting, arborizing blood vessels arranged in a retiform pattern, lined by monomorphic hobnail endothelial cells that showed minimal to mild cytologic atypia and no mitotic figures [1
]. In addition, many cases show a prominent lymphocytic infiltrate. Immunohistochemically, RH neoplasm endothelial cells react with vascular endothelial markers CD31, CD34, factor VIII-related antigen and bound Ulex europaeus agglutinin [5
]. In our case, the tumor cells showed typical morphological and immunophenotypical features of RH. There were minimal to mild cytological atypia no mitosis or necrosis. Ki-67 showed a proliferation rate of approximately of 10%. Multiple sections from the resection specimens were examined, showing no evidence of angiosarcoma. The case fulfilled the criteria for RH.
Our case showed several unusual and unique clinical features: multiple lesions, fast growing, and associated with sharp needle-stabbing like headache. The nature of the headache was atypical for a vascular tumor, and as a result, it was misdiagnosed as herpes zoster infection. The underlying causes of headache was unclear, but likely a result of vasospasm, secondary infection, bleeding, and ulceration of the scalp lesion. Up to now, only one case in the reported RH patients presented with a rapidly growing lesion [7
]; one case with multiple lesions located on trunk and extremities; and another case with a single lesion on the scalp reported[2
]. In our patient, although it is not clear if the second lesion behind the ear was another primary tumor or a tumor secondary to soft tissue metastasis of the scalp tumor, the proximity of the lesions as well as sequential occurrence of these two lesions would favor the later. It is noteworthy that there was no evidence of bone or intracranial invasion despite the large size of the scalp lesion, neither metastasis in the local lymph nodes.
The main differential diagnosis of includes cutaneous angiosarcoma, Dabska tumor [8
] and angiomatosis. Cutaneous angiosarcoma is a highly aggressive neoplasm with dismal prognosis and a very high incidence of local recurrence and metastasis and a high mortality rate [10
]. Histopathologically, angiosarcoma is featured by significant cytologic atypia, presence of conspicuous mitotic figures, tumor infiltrating between individual collagen bundles, and absence of hobnail endothelial cells [10
]. RH and Dabska's tumor share some common biologic behavior and histologic features. Some authors have considered that RH might represent the adult counterpart of Dabska's tumor and coined the term hobnail hemangioendo-thelioma to encompass both neoplasms [1
]. Unlike RH, Dabska's tumor occurs mostly in children and has slight predilection for the head and neck area. Histologically Dabska's tumor has well-formed papillary endothelial projections and lack of arborizing rete testis-like architecture. RH can be easily differentiated from cutaneous angiomatosis, which usually occurs in infants or young adults, and often involves a large segment of the body. Histologically, angiomatosis consists of large venous, cavernous as well as capillary-sized vessels that are usually located in the wall or adjacent to a large vein [12
RH has been considered to be a low grade angiosarcoma with a high incidence of recurrence. A wide surgical excision with histopathologically proven tumor-free margins is the optimal choice of RH treatment. Radiation therapy has also been proven effective in cases with lymph node metastasis [1
]. Our patient experienced tumor recurrence at the former scalp surgical field 3 months after surgery. The tumor recurrence was accompanied by similar nature of headache that she suffered before. She received care at local hospital and passed away at home 6 months after surgery. The immediate cause of death was unclear, but likely attributed RH. To our knowledge, this is the first case of RH related death reported.
In summary, our case showed many unusual clinical features, despite the typical histopathologic features of RH. This case illustrates an aggressive example of this tumor, which should prompt an accurate diagnosis and early intervention.