Extra-uterine myoid tumours in patients with acquired immunodeficiency syndrome: a clinicopathological reappraisal.

AIMS: AIDS-associated myoid tumours (AIDS-MTs), often Epstein-Barr virus (EBV)-associated (EBV-positive MTs), include smooth muscle tumors (SMTs) and the relatively recently recognized myopericytomas (MPCTs). The myoid immunophenotype of AIDS-MTs has been documented inconsistently. The aim of this study was to reappraise the phenotypic and immunophenotypic features of extra-uterine AIDS-MTs and the clinical profile of afflicted patients. METHODS AND RESULTS: EBV early RNA in-situ hybridization testing on 27 AIDS-MTs from 25 patients identified 19 of 27 (70.4%) EBV-positive MTs and eight of 27 (29.6%) EBV-negative MTs. EBV-positive MTs comprised 12 of 19 EBV-positive SMTs [six leiomyomas, one smooth muscle tumour of uncertain malignant potential (STUMP), five leiomyosarcomas] and seven of 19 EBV-positive MPCTs [benign (five), malignant (two)]. The EBV-negative MTs, made up exclusively of EBV-negative SMTs, included angioleiomyoma (one), leiomyoma (one), STUMP (one) and leiomyosarcomas (five). Malignant AIDS-MTs demonstrated hypercellularity, pleomorphism, increased mitoses and necrosis. EBV-positive leiomyosarcomas retained a conspicuous fascicular architecture. Four of five EBV-negative leiomyosarcomas demonstrated marked pleomorphism. All EBV-positive MPCTs and two EBV-positive leiomyosarcomas contained aggregates of desmin-negative round and oval cells. Seventeen of 25 patients died, mainly from comorbid diseases. CONCLUSION: While the reappraised spectrum of AIDS-MTs does not demonstrate divergent subtype-determined clinical behaviour, heightened awareness/recognition of this expanded spectrum will not only promote improved diagnosis of pleomorphic and myopericytic variants, which may be the sentinel clue to AIDS and its comorbidity, but will also facilitate distinction from histopathological mimics in specific anatomic locations.

Langerhans cells in anaplastic Kaposi sarcoma with a paucivascular phenotype: a potential diagnostic pitfall.

Anaplastic Kaposi sarcoma (AKS), a rare variant of Kaposi sarcoma, has a poorly recognized histomorphologic spectrum, including a paucivascular phenotype, that mimics a range of undifferentiated malignancies. This study, that highlights the hitherto undocumented phenomenon of S100-protein-positive Langerhans cells (SLCs) as a potential diagnostic pitfall in paucivascular AKS, involved review of nine such AKS that required diagnostic immunohistochemical (IHC) work-up. All biopsies had a predominant or exclusive spindle or epithelioid cell infiltrate. The first three tumors were diagnosed as malignant peripheral nerve sheath tumor (2) and metastatic melanoma (1), based on S100-protein immunopositivity. Biopsy of a co-existent pigmented sole lesion (patient 3) demonstrated nodular KS. Subsequent IHC investigation of these three tumors demonstrated an endothelial phenotype and HHV8 immunopositivity, confirming AKS. CD1a and langerin staining of the S100-protein-positive cells confirmed Langerhans cells as the cause of the diagnostic pitfall. Subsequently, six further paucivascular AKS with intratumoral SLCs were recognized on histomorphological and IHC appraisal. In conclusion, heightened awareness of the histomorphologic spectrum, appropriate IHC investigation, and informed appraisal thereof, are critical to the diagnosis of AKS with an undifferentiated phenotype, and the avoidance of IHC pitfalls, such as those caused by under-recognition and misinterpretation of bystander SLCs in AKS.