Unusual presentation of ectopic extramammary Paget disease.

Extramammary Paget disease (EMPD) is a malignant tumor typically found in apocrine-rich areas of the skin, particularly in the anogenital region. Some germinative apocrine-differentiating cells might exist on the trunk, preferentially in Asian individuals. Ectopic EMPD arises in nonapocrine-bearing areas, specifically the nongerminative milk line. We present a case of a 67-year-old Thai man with a slowly progressive, pruritic, erythematous to brown plaque on the right lower back of 30 years' duration. Histopathologic examination of 2 scouting biopsies revealed a proliferation of large cells with pleomorphic nuclei, prominent nucleoli, and abundant pale to clear cytoplasm within the epidermis. In one of the biopsies, tumor cells were found in the dermis with an infiltrative growth pattern. Immunohistochemically, the tumor cells were positive for cytokeratin 7, carcinoembryonic antigen, and gross cystic disease fluid protein 15. Based on these findings, a diagnosis of ectopic EMPD was made.

High-Velocity Paint Gun Injuries.

Cutaneous injuries due to industrial high-pressure paint guns are well-documented in the literature; however, the histologic characteristics are uncommonly described, and facial involvement has not been previously reported. Histopathologic features of paint gun injuries vary depending on the time since injection and type of material. Early lesions display an acute neutrophilic infiltrate, edema, and thrombosis, with varying degrees of skin, fat, and muscle necrosis. More developed lesions (120-192 hours after injury) have prominent histiocytes and fibrosis around necrotic foci, possibly with the pitfall of muscle regenerative giant cells that could be mistaken for sarcoma. Continuing inflammation, swelling, and resultant vascular compression could explain ongoing necrosis months after the accident. The histopathologic differential diagnosis in the absence of clinical history includes paint in an abrasion, foreign body reaction to tattoo, giant cell tumor of tendon sheath, and various neoplasms. If available, radiologic studies can substitute for clinical photographs to indicate the extent of injury. The radiologic differential, uninformed by history, may include calcific periarthritis, gouty tophus, and tumoral calcinosis. Seven cases of injury due to high-velocity paint guns are presented with 4 additional cases mimicking paint gun injury and with review of the literature.

Whole-exome sequencing identifies recurrent SF3B1 R625 mutation and comutation of NF1 and KIT in mucosal melanoma.

Mucosal melanomas are a rare subtype of melanoma, arising in mucosal tissues, which have a very poor prognosis due to the lack of effective targeted therapies. This study aimed to better understand the molecular landscape of these cancers and find potential new therapeutic targets. Whole-exome sequencing was performed on mucosal melanomas from 19 patients and 135 sun-exposed cutaneous melanomas, with matched peripheral blood samples when available. Mutational profiles were compared between mucosal subgroups and sun-exposed cutaneous melanomas. Comparisons of molecular profiles identified 161 genes enriched in mucosal melanoma (P<0.05). KIT and NF1 were frequently comutated (32%) in the mucosal subgroup, with a significantly higher incidence than that in cutaneous melanoma (4%). Recurrent SF3B1 R625H/S/C mutations were identified and validated in 7 of 19 (37%) mucosal melanoma patients. Mutations in the spliceosome pathway were found to be enriched in mucosal melanomas when compared with cutaneous melanomas. Alternative splicing in four genes were observed in SF3B1-mutant samples compared with the wild-type samples. This study identified potential new therapeutic targets for mucosal melanoma, including comutation of NF1 and KIT, and recurrent R625 mutations in SF3B1. This is the first report of SF3B1 R625 mutations in vulvovaginal mucosal melanoma, with the largest whole-exome sequencing project of mucosal melanomas to date. The results here also indicated that the mutations in SF3B1 lead to alternative splicing in multiple genes. These findings expand our knowledge of this rare disease.

Discordance Between Intraoperative Consultation by Frozen Section and Final Diagnosis.

Discrepancies between intraoperative consultations with frozen section diagnosis and the final pathology report have the potential to alter treatment decisions and affect patient care. Monitoring these correlations is a key component of laboratory quality assurance, however identifying specific areas for improvement can be difficult to attain. Our goal is to develop a standardized method utilizing root cause analysis and a modified Eindhoven classification schematic to identify the source of discrepancies and deferrals and subsequently to guide performance improvement initiatives. A retrospective review of intraoperative consultations performed at a tertiary level hospital and cancer center over a 6-month period identified deferrals and discrepancies between the intraoperative consult report and the final pathology report. We developed and applied a classification tool to identify the process errors and cognitive errors leading to discrepant results. A total of 48 (4.6%) discrepancies and 24 (2.3%) deferrals were identified from the 1042 frozen sections. Within the entire data set of frozen sections, the process errors (n = 26, 54.2%) were due to gross sampling (n = 16, 33.3%), histologic sampling (n = 8, 16.7%), and surgical sampling (n = 2, 4.2%). Interpretation errors (n = 22, 45.8%) included undercalls/false negatives (n=8, 16.7%), overcalls/false positives (n = 10, 20.8%), and misclassification errors (n = 4, 8.3%). Application of our classification tool demonstrated that the root cause of discrepancies and deferrals varied both between organ systems and by specific organs and that classification models may be utilized as a standardized method to identify focused areas for improvement.

Cutaneous decidualized endometriosis in a nonpregnant female: a potential pseudomalignancy.

Endometriosis is a disease process characterized by ectopic endometrial tissue. Involvement most commonly occurs in the lower pelvis, outside the uterine cavity, but can occur elsewhere, including the skin. Cutaneous endometriosis is a rare manifestation of this disease, with decidualization occurring in a very small minority of cases, almost always seen in pregnant females. Cutaneous involvement of endometriosis may present a diagnostic problem for the pathologist, particularly in the event of decidualization. Decidualization may mimic a malignancy and as a result may result in unnecessary diagnostic studies for the patient. We present a case of a nonpregnant patient with decidualized cutaneous endometriosis, discuss the histopathologic and immunohistochemical features of this entity, and review the pertinent literature on this subject. To our knowledge, this is the second reported case of cutaneous decidualized endometriosis in a nonpregnant female.