Lymphangioma-like Kaposi sarcoma: Case report
Published Web Locationhttps://doi.org/10.5070/D36193n4xk
Lymphangioma-like Kaposi sarcoma: Case reportComplexo Hospitalario de Pontevedra
Celia Posada García MD, Aranzazu García-Cruz, Ignacio García-Doval, Carlos De La Torre, Manuel José Cruces
Dermatology Online Journal 15 (9): 13
Kaposi sarcoma (KS) is a multifocal vascular disease with uncertain histogenesis. It is characterized by clinical and histologic polymorphism. The "lymphangioma-like" variant is very uncommon, accounting for less than 5% of all cases. We report the case of a 76-year-old woman, HIV negative, with a 4-year history of classic Kaposi sarcoma treated with cryotherapy who developed new bullous lesions on her lower extremities. Biopsy revealed histologic findings of lymphangioma-like KS (LLKS), together with areas of classic KS; HHV-8 staining was positive. Diagnosis of LLKS was made and the patient was proposed for radiotherapy. The lymphangioma-like Kaposi sarcoma is a rare morphologic expression of KS characterized by dilated and bizarrely shaped vascular channels lined by flattened endothelium permeating the dermis. "Bulla-like" lesions have been considered as a clinical hallmark of this variant. Its histologic appearance suggests a lymphatic origin of KS and it may resemble other vascular tumors. Findings of areas of typical KS and positive staining for HHV-8 may help to make a definitive diagnosis.
Lymphangioma-like Kaposi sarcoma (LLKS) is very uncommon, accounting for less than 5 percent cases of KS1. It occurs in virtually all of subtypes of the KS [1, 2, 3]. Its microscopic appearance may cause confusion with other benign and malignant vascular tumors .
|Figure 1. Compressible violaceous bulla-like lesions on the lower limb|
A 77-year-old woman, HIV negative, presented with a 4-year history of classic KS lesions treated with cryotherapy when necessary. During follow up, appearance of new violaceous bulla-like lesions on both legs, ankles and dorsal aspect of the feet was noticed, together with classic lesions of KS (Fig. 1). Otherwise no lymphedema or regional lymphadenopathy was evidenced on the affected limbs. Cutaneous biopsy revealed an angiomatous proliferation composed of dilated vascular channels lined by banal-appearing endothelia in the upper dermis coexisting with focal areas of classic KS (Fig. 2). HHV-8 staining was positive (Fig. 3). Diagnosis of LLKS was made and the patient was proposed for radiotherapy.
Lymphangioma-like Kaposi sarcoma is a rare morphologic expression of KS. The clinical features were first reported in 1957 by Ronchese and Kern , but Gange and Wilson-Jones  focused on the histological pattern in 1979.
Clinically, LLKS has not a specific manifestation [1, 3, 6]. LLKS can develop as typical-appearing KS but also as compressible bulla-like vascular lesions, which are considered a hallmark of this variant [1, 2, 6]. However, there are other lymphoedematous variants of KS which can present as bullous lesions either due to ectatic lymphatics (lymphangiectatic KS) or due to the accumulation of superficial dermal oedema (subepidermal bullous KS and intraepidermal bullous KS) . Very few cases described as "pseudo-bullous KS" have been reportedin absence of these histopathological features .
Development of bulla-like lesions in LLKS is still poorly understood. Chronic lymphedema, unique lower limb hemodynamics, and previous electron beam therapy have been proposed as predisposing factors [2, 6].
The histologic findings of the LLKS have been described as the presence of ectatic vascular channels lined by banal-appearing endothelia permeating the dermis without spindle cell proliferation [2, 5, 6]. According to Ramirez et al. , these histologic features generally represent a focal finding in otherwise typical KS (ill-defined spindle cell proliferation and "promontory" sign) that surrounds it. However, Gange and Wilson-Jones  did not find in their microscopic description areas of typical KS. When findings of typical KS are not evident, differential diagnosis with other vascular tumors may be difficult. These are benign lymphangioendothelioma, low-grade angiosarcoma, spindle cell hemangioendothelioma, retiform hemangioendothelioma and hobnail hemangioma [1, 3, 5]. Demonstration of HHV-8 in cutaneous lesions is a useful tool for differentiating KS from its mimics .
The histogenesis of KS remains uncertain. Controversy exists as to whether the endothelial cell is of vascular or lymphatic origin. Gange and Wilson Jones  initially postulated that LLKS variant could correspond to proliferation of lymphatic endothelium.
Clinical course of LLKS is usually characterized by a slowly progressive course. However, there is a report in literature that resulted in a fatal outcome .
Our case presented in a patient with previous history of classic KS and it developed as new bulla-like lesions together with previous classical KS lesions. Lymphedema was not present and no other therapies but cryotherapy had been attempted. Histologic examination showed a lymphangioma-like pattern but also areas of classical KS, which agrees with Ramirez's findings. Although the short follow up does not allow us to assure the evolution, the patient has responded to radiotherapy without disturbances in her general condition.
In conclusion, we report another case of LLKS, a rare morphologic variant of KS caractherized by a specific histologic pattern and variability of clinical lesions, considering bulla-like lesions indicative of this pattern. Its features suggest lymphatic endothelium origin. Differential diagnosis with other vascular tumors may be difficult. In these cases, findings of areas of typical KS and positive staining for HHV-8 may help to achieve a definitive diagnosis.
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