BAP1-deficient tumor/nevus with germline aberration: A potential pitfall in assessing melanocytic neoplasms with single nucleotide polymorphism array

BRCA1-associated protein 1 (BAP1) is a tumor suppressor gene, located on chromosome 3p21, encoding BAP1 nuclear protein, which is associated with a subset of melanocytic tumors with distinct cytologic features. Single nucleotide polymorphism array (SNP-array) is a molecular karyotyping technique that can detect copy number variations and loss of heterozygosity in various fresh and formalin-fixed paraffin-embedded tissues. Herein we present a 56-year-old female, who presented with a lesion on her left nose/cheek that was growing in size and changing in color. Histopathology was characteristic of a BAP1-deficient melanocytic neoplasm, with a biphasic population of cytologically bland conventional nevomelanocytes and a proliferation of large epithelioid melanocytes with abundant eosinophilic cytoplasm. Immunohistochemistry for BAP1 showed loss of nuclear labeling in the epithelioid melanocytes. SNP-array revealed a chromosome 21q22.1 monoaberration with no chromosome 3 abnormalities. The detection of this aberration prompted a discussion as to whether the lesion was best designated as a nevus or tumor. SNP-array on the patient's blood showed the same monoaberration of chromosome 21q22.1. This case emphasizes the importance of interpreting microarray results in the context of morphology, as germline aberrations can be a pitfall when assessing the genomic stability of a melanocytic proliferation by SNP array.

Monoclonal plasma cell infiltrates in the setting of cutaneous follicular helper T cell lymphoproliferative disorders

There is a growing recognition that some primary cutaneous T cell lymphomas of the skin exhibit a follicular helper T cell phenotype best exemplified by primary cutaneous CD4+ small/medium sized pleomorphic T cell lymphoma. The follicular helper T cells is an evolutionary function in a common TH1 cell under the influence of other cell types most notably monocyte derived dendritic cells but also plasma cells. In addition, the skin defines a characteristic organ site of involvement for angioimmunoblastic T-cell lymphoma (AITL); the first recognized form of follicular helper T cell lymphoma. One of the hallmarks of the follicular helper T cell lymphomas a significant degree of post germinal center B cell hyperplasia. We encountered 7 cases of primary cutaneous follicular helper T cell and four cases of AITL, in which the biopsies contained a light chain restricted plasma cell infiltrate in the skin. There were no features that suggested an atypical or more aggressive clinical course in association with the identification of this light chain restricted plasmacytic infiltrates except one case of AITL in whom a diffuse large cell B cell lymphoma subsequently developed. There was no association with Epstein-Barr virus (EBV) infection light chain restricted plasma cell infiltrate in any of the eleven cases. The basis of these infiltrates is likely a reciprocal functional one reflecting the role of follicular helper T cells in the induction of B cell hyperplasia and the role of plasma cells as a countercheck balance controlling the extent of follicular helper T cell hyperplasia. B cell clonality, plasma cell atypia and blastic B cell transformation can occur without implying a malignant transformation.

Association of IgG4 response and autoimmune pancreatitis with intraductal papillary-mucinous neoplasms

OBJECTIVES

Concurrent intraductal papillary-mucinous neoplasm (IPMN) and autoimmune pancreatitis (AIP) was observed in a patient (index case) at our institution. Cases of coincidental IPMN and type 1 AIP and concurrent ductal adenocarcinoma (PDAC) and AIP have been previously reported. In this study we evaluate the hypothesis that IPMN elicits an IgG4 response.

METHODS

Twenty-one pancreases (including the index case) with IPMN resected at our institution were studied. H&E stained slides were reviewed and blocks of peritumoral pancreas were immunostained with IgG4 to look for IgG4-positive plasma cells.

RESULTS

We found evidence of variable IgG4 overexpression in 4/21 (19%) of IPMN. These included the index case and three others without stigmata of AIP.

CONCLUSION

A small subset of pancreatic neoplasms including intraductal papillary-mucinous neoplasms (IPMN) is associated with an IgG4 autoimmune response that sometimes progresses to peritumoral type 1 AIP and less often to diffuse AIP and IgG4-related systemic disease.

Proliferative lesion of anogenital mammary-like glands in the setting of Cowden syndrome: case report and review of the literature

Mammary-like glands are normal appendages of anogenital skin and can give rise to epithelial and stromal tumors that closely resemble breast tumors. Cowden syndrome is an autosomal-dominant cancer-predisposition syndrome that is associated with increased risk of various benign and malignant tumors including breast cancers. Here, we report the first case of a proliferative lesion of mammary-like glands in the setting of Cowden syndrome. A 27-year-old female with Cowden syndrome (R130Q-PTEN mutation) presented with a 1-cm tender, polypoid perianal lesion. An excisional biopsy revealed a circumscribed, lobulated lesion with fibromyxoid stroma and epithelial hyperplasia with apocrine and columnar cell changes that was arranged in papillary, micropapillary and focal cribriform architecture. The features strikingly resembled proliferative changes commonly seen in the breast. Interestingly, the patient subsequently developed an atypical complex sclerosing lesion of the breast. Given the increased risk of breast neoplasia in Cowden syndrome, and the morphologic relationship between breast glands and mammary-like glands, this case raises the possibility of an increased risk of neoplasia arising in mammary-like glands in the setting of Cowden syndrome.