L. Jeffrey Medeiros

Angiocentric immunoproliferative lesions: A molecular analysis of eight cases

Angiocentric immunoproliferative lesions (AILs) are believed to represent a unique type of extranodal malignant lymphoma on the basis of clinicopathologic and immunophenotypic evidence. However, molecular studies to assess clonality have been performed on a small number of cases. In this study we assessed the clonality of eight AILs using restriction fragment analysis, the Southern blot technique, and probes to assess the configuration of the T-cell receptor beta, gamma, and delta chain genes and the immunoglobulin heavy and K light chain genes. In addition, the presence of the Epstein-Barr (EB) viral genome was assessed by using both Southern blot analysis (seven cases) and polymerase chain reaction amplification (five cases). Our results demonstrate that gene rearrangements are rare in AILs. A clonal gene rearrangement was identified in only one case, a grade III AIL with a rearrangement of the T-cell receptor delta chain gene. In two additional AILs (both grade III), the EB viral genome was detected as a single band by Southern blot analysis with a probe derived from the terminal repeat region of the virus, suggesting that a single episomal configuration of the EB viral genome was present in each case, as would occur in a clonal population of infected cells. In the remaining cases there was no evidence of clonality, although EB sequences were detected in one of four cases using the polymerase chain reaction. The rarity or absence of gene rearrangements in AILs is difficult to explain if AILs are malignant, presumably monoclonal lymphomas. However, their frequent association with the EB virus may suggest an analogy between AILs and lymphoproliferative disorders that occur in immunosuppressed patients. These findings further emphasize the unique clinicopathologic aspects of AILs and may also be useful diagnostically in the differential diagnosis of lymphoproliferative disorders.

Lymphoblastic lymphoma presenting in cutaneous sites: A clinicopathologic analysis of six cases

Six patients with malignant lymphoma of lymphoblastic type involving cutaneous sites at time of diagnosis are presented. Skin sites of the head and neck were involved in all patients and included the scalp (three patients), forehead (two patients), and malar region of the face (one patient). Two patients also had additional sites of skin disease (neck, breast, and anterior trunk). In two patients the skin was the predominant site of disease, whereas in the remaining patients staging workup revealed generalized lymphoma. The histologic findings in each patient were typical of lymphoblastic lymphoma; the neoplastic cells were small with blastic nuclear chromatin. In three patients the neoplastic cells were convoluted, and in three they were nonconvoluted. Immunophenotypically, four lymphomas were of pre-B cell type, and two lymphomas were of T cell type. There was no correlation between histologic features and the immunophenotype. Since the majority of lymphoblastic lymphomas are of T cell type, the predominance of pre-B cell tumors involving the skin may suggest that pre-B cell neoplasms have a predilection for cutaneous involvement. In further support of this hypothesis, both lymphomas that appear to have arisen in the skin had a pre-B cell immunophenotype.

Malignant schwannoma with melanocytic and neuroepithelial differentiation in an infant with congenital giant melanocytic nevus: A complex neurocristopathy

We describe an infant girl, born with a pigmented giant nevus, who developed a malignant schwannoma in the retroperitoneum at 16 months of age. At birth the nevus covered over 50% of her body and histologically was a compound nevus with extension into the deep dermis surrounding dermal appendages. The malignant schwannoma was biphasic with areas composed of spindle and round cells. Ultrastructurally, the majority of the tumor cells exhibited a Schwann cell phenotype, but neuroepithelial and melanocytic cells were identified as well. We believe that this constellation of findings represents a form of neurocristopathy. Neurocristopathy, as defined by Bolande (Hum Pathol 5:409-429, 1974), is a disease that results from aberrations in the migration, growth, or cytodifferentiation of neural crest tissues. These diseases may be simple (a singular pathologic process, usually localized) or complex (multiple neuroectodermal lesions). We report this case because the occurrence of retroperitoneal malignant schwannoma arising in a 16-month-old infant born with a pigmented giant nevus is unique, and may represent a previously undescribed form of a complex neurocristopathy.