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Table of Contents
Year : 2019  |  Volume : 37  |  Issue : 4  |  Page : 241-242

A case of kaposi sarcoma with focal clear cell change

1 Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan
2 Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital; Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan
3 Department of Dermatology, Taichung Veterans General Hospital; Department of Dermatology, National Yang-Ming University, Taipei, Taiwan

Date of Web Publication17-Dec-2019

Correspondence Address:
Dr. Chi-Shun Yang
No. 1650, Sec. 4, Taiwan Boulevard, Taichung 40705
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ds.ds_23_19

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How to cite this article:
Liao CY, Yang CS, Chen YJ. A case of kaposi sarcoma with focal clear cell change. Dermatol Sin 2019;37:241-2

How to cite this URL:
Liao CY, Yang CS, Chen YJ. A case of kaposi sarcoma with focal clear cell change. Dermatol Sin [serial online] 2019 [cited 2023 Feb 2];37:241-2. Available from: https://www.dermsinica.org/text.asp?2019/37/4/241/273099

Dear Editor,

Kaposi sarcoma (KS) is a low-grade angioproliferative tumor arising from lymphatic endothelial cells. In addition to classic patch, plaque, and nodular histological stages, several variants have been documented, including the anaplastic, lymphangioma-like, lymphangectatic, cavernous hemangioma-like, ecchymotic, telangiectatic, bullous, micronodular, glomeruloid, hyperkeratotic, keloidal, pigmented, pyogenic granuloma-like, intravascular, KS with myoid nodules and regressive KS variants.[1],[2],[3],[4] To the best of our knowledge, KS with clear cell change has never been reported in the English literature thus far.

A 65-year-old man with a history of classic KS over the left lower limb status postradiotherapy and chemotherapy 6 years ago presented to our hospital with tumor progression and an open wound over his left ankle. Grossly, there are multiple clusters of violaceous to blackish hyperkeratotic papules and nodules around the inner thigh and several huge exophytic verrucous tumors with overlying yellowish exudate near the popliteal fossa [Figure 1]a. Left hip disarticulation with reconstruction rotation flap was performed because of the refractory response to previous treatment and wound infection. Pathologically, most of the tumor cells demonstrated classic KS lesions in the plaque and nodular stages. The other unique morphological subtypes, namely intravascular, pyogenic granuloma-like, and telangiectatic KS, were also observed [Figure 1]b, [Figure 2]C, [Figure 2]d. Moreover, scattered single and grouped clear cells with centrally or eccentrically located vesicular nuclei with mild cytologic atypia and extravasated erythrocytes were arranged in a solid sheet-like growth pattern resembling metastatic clear cell renal cell carcinoma. The clear cell change constitutes <5% of the main tumor [Figure 2]a and [Figure 2]b. Immunohistochemical staining of the clear cell were positive for human herpesvirus 8 (HHV8), CD34, and D2-40 [Figure 2]c and d] but were nonreactive for cytokeratin, CD10, and CAIX. This confirmed the presence of an unusual histological pattern of KS.
Figure 1: (a) Multiple violaceous to blackish hyperkeratotic papules, nodules and several huge verrucous tumors with yellowish exudate around the inner thigh and popliteal fossa, (b) intravenous spindle cells proliferation with slit-like spaces and erythrocytes extravasation, (c) dilated, thin-walled and congested vascular channels mimicking cavernous hemangioma, (d) polypoid and ulcerative spindle cell tumor containing dilated vessels simulating pyogenic granuloma

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Figure 2: (a) Tumor cells with pale-to-clear cytoplasm arranged in a sieve-like pattern (H and E, ×100), (b) tumor cells with an eccentrically or centrally located vesicular nucleus and mild cytologic atypia intermix with extravasated erythrocytes (H and E, ×400), (c) Immunohistochemical staining showing diffuse positive staining for human herpesvirus 8 in a nuclear pattern (×200) and for (d) D2-40 over the tumor cells (×200)

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In the present case, the tumor cells revealed several unique histological patterns of KS, which may post diagnostic challenges. The intravascular pattern revealed intravenous spindle cell KS proliferation which leads to various differential diagnoses, including intravascular pyogenic granuloma, intravascular fasciitis, intravascular papillary endothelial hyperplasia, papillary intralymphatic angioendothelioma, and intravascular myopericytoma. The telangiectatic pattern composed of thin-walled and dilated blood vessels congested with erythrocytes mimicked cavernous hemangioma. The pyogenic granuloma-like KS demonstrated a polypoid configuration with ulceration and inflammatory cells infiltration which may have led to a misdiagnosis as pyogenic granuloma.[1],[2],[3] The most notable feature was the clear cell change of KS. The epithelioid cells with clear cytoplasm and mild cellular atypia arranged in a sheet-like growth pattern are reminiscent of the sieve-like spaces in the plaque and nodular stage of KS, which is attributable to the haphazardly arranged fascicular spindle cells cut in cross-section.[1] However, no intersecting fascicles of monomorphic spindle cells admixed with the sieve-like epithelioid cells were noted.

KS with clear cell change needs to be differentiated from the various other primary or metastatic cutaneous clear cell neoplasms with epithelial, mesenchymal, and melanocytic differentiation. The cytoplasmic clearing of tumor cells is mostly attributable to the intracellular storage of lipid, mucin, or glycogen, to a degenerative process, or sometimes to an artifact or reactive response.[5],[6] According to the histological growth pattern, degree of cytologic atypia, cause of clear cell change, and individual cytomorphology, the most likely differential diagnoses included clear cell hidradenoma, metastatic clear cell renal cell carcinoma, clear cell melanoma, and epithelioid clear cells angiosarcoma. Hidradenoma is a well-circumscribed and multilobulated tumor with intradermal epithelial proliferation and evident ductal differentiation. Clear cell hidradenoma is a morphological variant containing abundant glycogen within tumor cells. Metastatic renal cell carcinoma is one of the most common cutaneous metastases of internal malignancy that demonstrates clear cell change. Histologically, metastatic renal cell carcinoma shows a dermal nodule composed of monomorphically proliferated clear cells containing lipid and glycogen with well-delineated cell borders, small nuclei, delicate and highly vascular stroma, and intratumoral hemorrhage. Clear cell melanoma is characterized by the presence of clear cells with centrally located hyperchromatic nuclei and cytoplasmic vacuolation, with occasional signet ring change.[5],[6] Epithelioid clear cell angiosarcoma may demonstrate considerable resemblance to clear cell KS. Nevertheless, the aforementioned epithelioid clear cell angiosarcoma is characterized by the presence of nuclear pleomorphism, prominent nucleoli, and increased mitotic activity and the absence of HHV8 immunohistochemical staining.[7],[8]

In summary, we described a new morphological feature of KS with clear cell change. The clinical prognosis of this new variant is yet to be determined. Pathologists and dermatopathologists need to become familiar with this newly described histological KS subtype to prevent potential misdiagnosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest

  References Top

Grayson W, Pantanowitz L. Histological variants of cutaneous Kaposi sarcoma. Diagn Pathol 2008;3:31.  Back to cited text no. 1
O'Donnell PJ, Pantanowitz L, Grayson W. Unique histologic variants of cutaneous Kaposi sarcoma. Am J Dermatopathol 2010;32:244-50.  Back to cited text no. 2
Sutton AM, Tarbox M, Burkemper NM. Cavernous hemangioma-like Kaposi sarcoma: A unique histopathologic variant. Am J Dermatopathol 2014;36:440-2.  Back to cited text no. 3
Cetin B, Aktas B, Bal O, Algin E, Akman T, Koral L, et al. Classic Kaposi's sarcoma: A review of 156 cases. Dermatol Sin 2018;36:185-9.  Back to cited text no. 4
Smith EH, Andea AA. Cutaneous clear cell neoplasms: A systematic review. Diagn Histopathol 2016;22:134-41.  Back to cited text no. 5
Biswas A, Mahalingam M. Cutaneous clear cell neoplasms: A histopathological reappraisal. Am J Dermatopathol 2012;34:237-54.  Back to cited text no. 6
Bacchi CE, Silva TR, Zambrano E, Plaza J, Suster S, Luzar B, et al. Epithelioid angiosarcoma of the skin: A study of 18 cases with emphasis on its clinicopathologic spectrum and unusual morphologic features. Am J Surg Pathol 2010;34:1334-43.  Back to cited text no. 7
Ko JS, Billings SD. Diagnostically challenging epithelioid vascular tumors. Surg Pathol Clin 2015;8:331-51.  Back to cited text no. 8


  [Figure 1], [Figure 2]


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