Disseminated Kaposi sarcoma with cutaneous lesions on a surgical scar in a kidney transplant recipient

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Kaposi sarcoma (KS) is a rare, polyclonal angioproliferative mesenchymal neoplasm caused by human herpes virus type-8 (HHV-8). Iatrogenic KS occurs in patients receiving long-term immunosuppressive treatments and in organ transplant recipients. The occurrence of KS in a kidney transplant surgical scar is extremely rare.

A 36-year-old woman, who underwent a right kidney transplant 18 months ago for chronic renal failure caused by chronic interstitial nephropathy, presented with cutaneous nodules in the abdominal wall with a deterioration in general condition evolving for 3 months. Her immunosuppressive therapy included prednisone (5 mg) daily and mycophenolate mofetil (500 mg) once daily. Dermatological examination revealed the presence of non-painful, well-defined, purplish-blue, nodular lesions along the surgical scar measuring 0.5 to 2 cm [Figure 1a]. The rest of the cutaneous and mucosal examination was unremarkable. The main differential diagnoses included sarcoidosis on a surgical scar, angiosarcoma, bacillary angiomatosis, and cutaneous metastases. The general examination revealed asthenia, bilateral inguinal and cervical lymphadenopathy, and a painless, indurated mass extending from the left iliac fossa to the hypogastrium. Dermoscopy showed a rainbow pattern with white lines, clods, and surface scales [Figure 1b]. The histological analysis of both skin and abdominal mass biopsies revealed an infiltrative proliferation of spindle cells with slit-like vascular channels and extravasated erythrocytes [Figure 2a]. Immunohistochemical staining for HHV8 was positive in the tumour cells [Figure 2b]. Following the diagnosis, HHV-8 serology was performed and found to be positive. Imaging revealed multiple intraperitoneal masses [Figure 3a], along with hepatic [Figure 3b] and pulmonary nodules [Figure 3c], and a biopsy was performed for further evaluation. An esophagogastroduodenoscopy showed an ulcerated polypoid formation in the oesophagus, of which the biopsy was compatible with KS. The diagnosis of cutaneous and visceral KS was made. The treatment was based on the reduction of the immunosuppressive treatment and the introduction of an inhibitor of the mTOR protein (SIROLIMUS). The patient was treated with systemic chemotherapy (bleomycin). Regression of the lesions began after 3 months, with disappearance of the skin lesions and reduction of the abdominal mass [Figure 4]. Graft function remained stable throughout the treatment period with no reported episodes of rejection.

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Figure 1:

(a) Well-defined purplish-blue nodules (0.5-2 cm) along the surgical scar. (b) Dermoscopy showing a rainbow pattern with white lines, clods, and surface scales (DermLite DL4, polarised 10x).

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Figure 2:

(a) Skin biopsy showing an infiltrative spindle cell proliferation with slit-like vascular channels and extravasated erythrocytes (Haematoxylin and eosin, 100x). (b) Positive immunostaining of tumour cells for HHV8 (100x).

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Figure 3:

Contrast-enhanced abdominal CT scan demonstrating enhancing intraperitoneal soft tissue masses a), (blue stars), associated with multiple hypodense hepatic nodules b), (blue arrows). c) Thoracic CT scan in lung window setting reveals solid pulmonary nodules (red arrows).

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Figure 4:

Resolution of cutaneous nodules during follow-up.

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Iatrogenic KS, first described in 1970 in organ transplant patients, is a subtype that occurs in individuals under long-term immunosuppressive treatments, regardless of the organ transplantation context.¹ It is common in kidney transplant recipients. Onset can occur from 2 months to 22 years post-transplant, with the highest risk in the first 2 years when immunosuppression is greatest.² Iatrogenic KS results in cutaneous-mucosal or visceral lesions with extent depending on immunosuppression level, leading to multifocal, florid lesions. Oral mucosa is involved in 20% of cases, with visceral dissemination in 20-50% of cases.² The occurrence of Kaposi disease lesions on the surgical scar is extremely rare. The proposed theory involves the Koebner phenomenon, where skin trauma from surgery triggers the release of basic fibroblast growth factor (b-FGF), stimulating local HHV8 replication and increasing binding protein expression. This trauma also releases other growth factors, including interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and granulocyte-macrophage colony-stimulating factor (GM-CSF), promoting angiogenesis and Kaposi’s sarcoma lesions.³ While Kaposi sarcoma is commonly suspected clinically, dermoscopy enhances diagnostic accuracy. The presentation resembles lesions in non-scar areas. Key dermoscopic features include white lines, white clots, surface scale, polychromatic colour changes, collaretted sign, vessels, and a purple-pink color.⁴ A biopsy is mandatory for diagnosis, with histology identical across epidemiologic types. Immunohistochemistry using a monoclonal antibody against HHV8 latent nuclear antigen on paraffin-embedded sections is essential. Histological differential diagnoses include angiosarcoma and bacillary angiomatosis, which may mimic KS in some cases.

Regarding therapeutic management, reducing immunosuppressive treatment is the cornerstone for managing KS post-transplantation, along with introducing an mTOR inhibitor for its anti-tumor properties.⁵ Systemic chemotherapy is indicated for progressive disease and cases with visceral involvement.¹ For cutaneous lesions, therapeutic options include surgical excision, particularly in pauci-lesional forms with significant functional impairment. Cryosurgery may be considered for limited and indolent lesions. Intralesional chemotherapy is another possible approach, while radiotherapy can be used for localised lesions not amenable to surgery. The prognosis of transplant-associated KS is variable. The prognosis can be life-threatening in cases of widespread dissemination with multivisceral involvement, and graft function may be impaired during the course of this disease.