Carlos N. Prieto-Granada

Loss of H3K27me3 Expression Is a Highly Sensitive Marker for Sporadic and Radiation-induced MPNST.

Most malignant peripheral nerve sheath tumors (MPNSTs) exhibit combined inactivation of NF1, CDKN2A, and polycomb repressive complex 2 component genes (Embryonic Ectoderm Development [EED] and Suppressor of Zeste 12 [SUZ12]). Mutations in EED and SUZ12 induce loss of trimethylation at lysine 27 of histone 3 (H3K27me3), with subsequent aberrant transcriptional activation of polycomb repressive complex 2–repressed homeobox master regulators. These findings prompted us to investigate the performance of an anti-H3K27me3 monoclonal antibody clone C36B11 as an immunohistochemical marker for MPNSTs. We assessed the C36B11 reactivity pattern in a pathologically and genetically well-characterized cohort of 68 MPNSTs, spanning various clinical presentations, such as type 1 neurofibromatosis (NF1), radiotherapy, and sporadic MPNSTs. We found that 69% (n=47) of all MPNSTs demonstrated loss of H3K27me3 expression, with 42 (61%) showing complete loss and 5 (7%) showing partial loss, whereas 31% (n=21) retained H3K27me3 expression. Among the NF1-related high-grade MPNSTs, 60% demonstrated loss of expression. In contrast, the majority of both sporadic (95%) and radiotherapy-related (91%) MPNSTs showed loss of H3K27me3 expression. Two of the 3 low-grade MPNSTs and all neurofibromas showed retained expression. Furthermore, all 5 epithelioid MPNSTs retained H3K27me3 labeling. The specificity of H3K27me3 loss as a marker for MPNSTs was studied by testing a large spectrum of lesions included in MPNST differential diagnosis, such as spindle/desmoplastic melanomas, synovial sarcomas, myoepithelial tumors, and other mesenchymal neoplasms, all of which retained expression of H3K27me3. We conclude that immunohistochemical analysis of H3K27me3 has good sensitivity and robust specificity for the diagnosis of MPNST, particularly outside of NF1 clinical history, which represents the most challenging diagnostic setting.

A Genetic Dichotomy between Pure Sclerosing Epithelioid Fibrosarcoma (SEF) and Hybrid SEF/Low Grade Fibromyxoid Sarcoma: A Pathologic and Molecular Study of 18 cases

Sclerosing epithelioid fibrosarcoma (SEF) is a rare soft tissue tumor exhibiting considerable morphologic overlap with low‐grade fibromyxoid sarcoma (LGFMS). Moreover, both SEF and LGFMS show MUC4 expression by immunohistochemistry. While the majority of LGFMS cases are characterized by a FUS‐CREB3L1 fusion, both FUS‐CREB3L2 and EWSR1‐CREB3L1 fusions were recently demonstrated in a small number of LGFMS and SEF/LGFMS hybrid tumors. In contrast, recent studies pointed out that SEF harbor frequent EWSR1 rearrangements, with only a minority of cases showing FUS‐CREB3L2 fusions. In an effort to further characterize the molecular characteristics of pure SEF and hybrid SEF/LGFMS lesions, we undertook a clinicopathologic, immunohistochemical and genetic analysis of a series of 10 SEF and 8 hybrid SEF/LGFMS tumors. The mortality rate was similar between the two groups, 44% within the pure SEF group and 37% in the hybrid SEF/LGFMS with a mean overall follow‐up of 66 months. All but one pure SEF and all hybrid SEF/LGFMS‐tested cases showed MUC4 immunoreactivity. The majority (90%) of pure SEF cases showed EWSR1 gene rearrangements by fluorescence in situ hybridization with only one case exhibiting FUS rearrangement. Of the nine EWSR1 positive cases, six cases harbored CREB3L1 break‐apart, two had CREB3L2 rearrangement (a previously unreported finding) and one lacked evidence of CREB3L1/2 abnormalities. In contrast, all hybrid SEF/LGFMS tumors exhibited FUS and CREB3L2 rearrangements. These results further demarcate a relative cytogenetic dichotomy between pure SEF, often characterized by EWSR1 rearrangements, and hybrid SEF/LGFMS, harboring FUS‐CREB3L2 fusion; the latter group recapitulating the genotype of LGFMS.

Predictors of Outcome in Adenoid Cystic Carcinoma of Salivary Glands: A Clinicopathologic Study With Correlation Between MYB Fusion and Protein Expression

Adenoid cystic carcinoma (ACC) is the second most common salivary gland malignancy and it has a high rate of recurrences and a poor long-term prognosis. Our aim was to assess the prognostic factors in ACC and study MYB-NFIB fusion and MYB protein expression in a large retrospective cohort of 135 patients with a median follow-up of 6.3 years. The 5- and 10-year local recurrence-free survival (RFS) rate of 94% and 78%, 5- and 10-year distant metastasis survival rate of 77% and 58%, and 5- and 10-year RFS of 66% and 44%. The following features were identified as adverse prognostic factors of RFS on univariate analysis: large tumor size, solid growth pattern, increased mitoses, positive margin, American Joint Committee on Cancer clinical staging, high-grade transformation, vascular invasion, nuclear atypia, open chromatin, prominent nucleoli, and tumor necrosis. However, on multivariate analysis, only increased mitoses (≥5/10 high-power fields), any solid growth pattern, and advanced American Joint Committee on Cancer TNM staging were independent adverse predictors for RFS. MYB immunoexpression and MYB-NFIB translocation were common findings in ACC, occurring in 72% and 59% of the tested ACCs, respectively. The sensitivity and specificity of MYB immunohistochemistry in detecting MYB-NFIB fusion was relatively low at 78% sensitivity and 50% specificity. The high prevalence of alterations leading to high expression of the MYB transcription factor family suggests that targeted approaches developed to suppress the expression of these oncogenic transcription factors and/or the transcriptional activity of these proteins would be a rational therapeutic approach to investigate in ACC.

Primary renal sclerosing epithelioid fibrosarcoma: report of 2 cases with EWSR1-CREB3L1 gene fusion.

We report the first 2 genetically confirmed cases of primary renal sclerosing epithelioid fibrosarcoma (SEF), occurring in a 17-year-old boy and a 61-year-old woman. In both cases, the tumors demonstrated the typical epithelioid clear cell morphology associated with extensive hyalinizing fibrosis, raising the differential diagnosis of solitary fibrous tumor, metanephric stromal tumor, and the sclerosing variant of clear cell sarcoma of the kidney. Both neoplasms demonstrated diffuse immunoreactivity for MUC4, a highly specific marker for SEF, and both demonstrated evidence of rearrangement of both the EWSR1 and CREB3L1 genes, which have recently been shown to be fused in this entity. Both neoplasms presented with metastatic disease. Primary renal SEF represents yet another translocation-associated sarcoma now shown to arise primarily in the kidney.

Cutaneous squamous cell carcinoma and related entities: Epidemiology, clinical and histological features, and basic science overview.

Cutaneous squamous cell carcinoma (cSCC) corresponds to approximately 20% of all nonmelanoma skin cancer (NMSC) cases and is currently the second most common human malignancies worldwide, trailing behind only basal cell carcinoma (BCC). However, in contrast with BCCs, certain aggressive cSCC variants as well as tumors equal to or larger than 2 cm in diameter and 2 mm in thickness exhibit a much more aggressive clinical behavior with significant risk for local recurrence and distant metastases. We review various aspects of cSCC, including its precursor and related entities: actinic keratosis (AK) and keratoacanthoma (KA). We include up to date epidemiologic data, clinical and histopathologic presentations, as well as the molecular alterations present in these entities.

Lymph node extramedullary hematopoiesis in breast cancer patients receiving neoadjuvant therapy: A potential diagnostic pitfall

Extramedullary hematopoiesis (EMH) develops as a compensatory mechanism associated with hematologic processes but it may occur in association with chemotherapy. Three cases of EMH arising in axillary lymph nodes following neoadjuvant therapy for breast carcinoma are reported herein. Three women ranging in age from 41 to 47 years presented with unilateral breast masses measuring 0.6 to 4.0 cm in greatest dimension and were diagnosed with infiltrating ductal carcinoma, grade III by core needle biopsies. Two of the tumors were triple negative and one was estrogen receptor positive. All patients subsequently received neoadjuvant therapy followed by lumpectomies. No residual carcinoma was identified in postchemotherapy breast resection specimens. One patient underwent a sentinel lymph node procedure, the second patient an axillary lymph node dissection, and the third patient had a core biopsy of an enlarged axillary lymph node. The patient that underwent axillary lymph node dissection had metastatic carcinoma in one of her lymph nodes. Foci of EMH consisting of myeloid, erythroid, and megakaryocytic precursors were present within the nodal parenchyma and/or subcapsular sinuses of axillary lymph nodes of all three cases. Megakaryocytes were immunoreactive with factor VIII, erythroid elements with Glycophorin and myeloid precursors with myeloperoxidase. With increasing use of neoadjuvant therapy for breast carcinoma, EMH within lymph nodes is more likely to be encountered. Hematopoietic precursors present in lymph nodes may potentially be misdiagnosed as metastatic tumor cells, particularly as lobular carcinoma or metaplastic carcinoma. Therefore, caution should be exercised when evaluating axillary lymph nodes in the clinical setting of neoadjuvant therapy for breast carcinoma.

Comparing whole slide digital images versus traditional glass slides in the detection of common microscopic features seen in dermatitis.

Background: The quality and limitations of digital slides are not fully known. We aimed to estimate intrapathologist discrepancy in detecting specific microscopic features on glass slides and digital slides created by scanning at ×20. Methods: Hematoxylin and eosin and periodic acid-Schiff glass slides were digitized using the Mirax Scan (Carl Zeiss Inc., Germany). Six pathologists assessed 50-71 digital slides. We recorded objective magnification, total time, and detection of the following: Mast cells; eosinophils; plasma cells; pigmented macrophages; melanin in the epidermis; fungal bodies; neutrophils; civatte bodies; parakeratosis; and sebocytes. This process was repeated using the corresponding glass slides after 3 weeks. The diagnosis was not required. Results: The mean time to assess digital slides was 176.77 s and 137.61 s for glass slides (P < 0.001, 99% confidence interval [CI]). The mean objective magnification used to detect features using digital slides was 18.28 and 14.07 for glass slides (P < 0.001, 99.99% CI). Parakeratosis, civatte bodies, pigmented macrophages, melanin in the epidermis, mast cells, eosinophils, plasma cells, and neutrophils, were identified at lower objectives on glass slides (P = 0.023-0.001, 95% CI). Average intraobserver concordance ranged from κ = 0.30 to κ = 0.78. Features with poor to fair average concordance were: Melanin in the epidermis (κ = 0.15-0.58); plasma cells (κ = 0.15-0.49); and neutrophils (κ = 0.12-0.48). Features with moderate average intrapathologist concordance were: parakeratosis (κ = 0.21-0.61); civatte bodies (κ = 0.21-0.71); pigment-laden macrophages (κ = 0.34-0.66); mast cells (κ = 0.29-0.78); and eosinophils (κ = 0.31-0.79). The average intrapathologist concordance was good for sebocytes (κ = 0.51-1.00) and fungal bodies (κ = 0.47-0.76). Conclusions: Telepathology using digital slides scanned at ×20 is sufficient for detection of histopathologic features routinely encountered in dermatitis cases, though less efficient than glass slides.

Lethal melanoma in children: a clinicopathological study of 12 cases

Melanoma in children is rare, representing 3% of paediatric malignancies and <1% of all melanomas. Very few detailed descriptions of bona fide lethal childhood melanomas exist in the literature. We performed a retrospective clinicopathological review of 12 paediatric (≤16 years) melanoma patients who died of metastatic disease, including detailed assessment of architectural and cytomorphological features. There were nine prepubertal patients (median age 7 years old) and three postpubertal cases (median age 15 years old). The patients died on average 45.7 months after diagnosis with the prepubertal subcohort showing a relatively longer time from diagnosis to death. The tumours were bulky (average tumour thickness=10mm), showed brisk mitotic activity (average mitotic count per mm2=7), and were formed by large expansile nodules with sheet-like growth pattern and infiltrative borders in the majority of cases (83%). Cytologically, large grossly pleomorphic epithelioid cells with massive eosinophilic macronucleoli were present in most cases (75%). In this cohort, we did not identify specific features of melanoma that were unique to children. Although melanomas are extremely rarely encountered in childhood, the above-cited unequivocal malignant features should prompt an outright diagnosis of melanoma even in a paediatric patient.

Thymic Mucoepidermoid Carcinoma: Report of a Case With CTRC1/3-MALM2 Molecular Studies

Thymic mucoepidermoid carcinoma (TMEC) is a vanishingly rare entity that usually presents as low to intermediate grade MEC and carries a better prognosis when compared with other poorly differentiated thymic carcinomas. The recently described fusions, t(11;19)(q21;p13) CREB (cAMP response element-binding protein)-regulated transcription coactivator 1 and MAML2, mastermind-like gene 2 (CRTC1-MAML2) and t(11:15)(q21;q26) CRTC3-MAML2 characterize a considerable proportion of MEC examples arising from a variety of anatomical sites. Recent data point out that the aberrant proteins produced by this fusion drive oncogenesis by disrupting the cAMP/CREB and NOTCH1 pathways. To date, only 2 TMEC cases have been reported to have MAML2 rearrangements, a feature that was found to be absent in TMEC mimics. These findings led the authors to recommend this test as a diagnostic tool in the differential diagnosis for thymic carcinoma. Herein, we present a case of TMEC arising in a 58-year-old woman, which was predominantly cystic with intracystic papillary formations composed of a mixture of mucinous cells and intermediate/epidermoid eosinophilic cells. This case was negative for CTCR1-MAML2 and CTCR3-MAML2 fusion transcripts by reverse transcriptase polymerase chain reaction and lacked a MAML2 rearrangement by fluorescence in situ hybridization. We report a CTCR1/3-MAML2 fusion and MAML2 rearrangement–negative TMEC, indicating that a different molecular pathway must be involved in the generation of these tumors. The possibility of fusion-negative TMEC should be taken into consideration in the differential diagnosis of a thymic carcinoma.

Basal cell carcinoma: Epidemiology, clinical and histologic features, and basic science overview

Basal cell carcinoma (BCC) is a quite ubiquitous entity in dermatology and dermatopathology, and, together with cutaneous squamous cell carcinoma (cSCC), constitutes the bulk of the socalled “nonmelanoma skin cancer” (NMSC) cases. Both BCC and cSCC arise in a similar clinical background of chronic sun damage and immunosuppression, among other risk factors. However, it is important to emphasize that BCC represents more of a locally aggressive tumor that rarely metastasizes, compared with cSCC, particularly some subtypes, which may have a higher risk of metastatic spread and even death. BCC can be classified into several variants that demonstrate different clinical behaviors, particularly in terms of local recurrence rates. We review the different facets of BCC to include up to date epidemiologic data, clinical and histopathologic presentations, as well as the latest findings on the molecular alterations driving this entity.