DEAR EDITOR, Kaposi sarcoma (KS) is an angioproliferative malignancy, subclassified into classic, African (endemic), AIDS-related and iatrogenic type. 1 A new subgroup of patients with KS has been increasingly recognizedmen who have sex with men (MSM), but who are HIV-seronegative and have no identifiable immunodeficiency. Herein, we describe a series of patients who do not fit into the current classification system for KS.Between 1997 and 2011, eight HIV-seronegative MSM patients with histologically confirmed KS were identified from the personal archives of the authors (one patient from Lewisham Hospital; seven from Chelsea and Westminster Hospital). The median age of the patients was 53 years (range 37-65). Seven (88%) patients were white British, and one patient was of Hong Chinese descent. Four (50%) patients were skin type I, three (38%) were skin type II and one (12%) was skin type IV. The number of KS lesions varied from one to 50, with a median of four lesions. Two (25%) patients had only one KS lesion. Four (50%) patients had KS lesions confined to their lower limbs, and three (38%) patients had both upper and lower limb involvement. One patient had a single lesion located on the temple.At the time of KS diagnosis, two (25%) patients had KS-associated herpesvirus (KSHV) viraemia, with detectable plasma KSHV DNA (570 and 700 copies mL À1 , respectively). Immunohistochemistry for KSHV latent nuclear antigen 8 was positive for all cases. The histological grade of KS for six (75%) patients was of nodular grade; one patient had angiomatoid grade KS; and one patient had an unspecified grade of KS. The primary therapy for six (75%) patients was surgical excision. For the remaining two patients, the KS was treated with radiotherapy (n = 1) and systemic chemotherapy (n = 1). After a median follow-up of 3Á7 years (0Á2-15), all patients were alive.Only a few sporadic reports regarding KS in HIV-seronegative MSM have been published. In 1986, Marquart et al. 2 described the case of a 44-year-old HIV-seronegative bisexual man who developed a slowly progressing KS nodule on the glans penis. Garc ıa-Muret et al. reported the case of a 42-year-old white bisexual HIV-seronegative man with disseminated KS limited to the skin and gastrointestinal tract. The CD4/CD8 ratio was normal, and the KS remained indolent over a 30-month follow-up period. 3 Kua et al.reported the case of 53-year-old man who had sex with men and who had KS of the buccal mucosa. The patient was HIV-seronegative with no other cause of immunodeficiency identified. 4 Six HIV-seronegative MSM patients were described by Friedman- Kien et al. in 1990. 5 The mean age of the group was 45 years (range 32-62). Three of the patients had KS lesions limited to the legs only, with two patients developing a single KS lesion on the penis. 5 Lanternier et al. 6 published the largest case series thus far. The series, covering a 12-year period, consisted of 28 HIV-seronegative MSM patients with histologically proven KS. 6 The mean age at diagnosis in this cohort was 55 y...