Boland, Jennifer M.

Context.— A clinic was created for patients to review their explanted organs with a pathologist. Objective.— To prospectively investigate the benefits of this type of clinic as perceived by both transplant patients and their pathologists. Design.— In this prospective study, patients participated in a videotaped viewing of heart and/or lung explants by the patient and their guest(s) and pathologist (December 2017–August 2022). Patients received a 3D-printed replica of their explant. After viewing the explanted organ, patients and their guests participated in an interview to assess their experiences. Video-reflexive ethnography was used by pathologists for data collection and practice improvement. Results.— Of 143 patients who viewed their explanted organ, 21 patients consented to having the organ-viewing session taped and to participate in a postviewing interview. The study group was comprised of 12 men; the median age was 57.5 years (range, 29–67 years). Five pathologists took part in reflexive sessions. The clinics were viewed positively by patients, providing an opportunity to better understand their disease. Pathologists had a similarly positive experience and gained important insights to patient journeys. Proposals for improvement were brought forward from both patients and pathologists. Conclusions.— Video-reflexive ethnography provided the opportunity for patients and pathologists to reflect on patient-pathology clinic appointments. This work serves as a template to build out pathology-based clinics.

Context.— Cardiac and pulmonary allograft recipients represent a unique population, frequently interacting with support groups and exhibiting intense curiosity about their pathology. Like other solid organ transplant patients, they have enduring and frequent interaction with the laboratory for routine allograft surveillance. Objective.— To address patient requests to understand what happens to their explanted organ and to better understand their disease while simultaneously improving awareness of pathologists’ roles in their continuing care. Design.— At routine follow-up appointments, transplant nurse coordinators offer each allograft recipient the opportunity to interact with a pathologist in our “ On My Path ” program. Organ viewing occurs in a private setting, in a specialized room. Relevant pathology is discussed, and questions are answered, with documentation in the medical record. The patient is subsequently gifted a 3-dimensional model of their explanted organ. Transplant coordinators were surveyed for their feedback on the experience. Results.— One hundred fifty-eight interactions have been documented (2017–2022) at our institution, including patients who underwent cardiac transplant (96, 61%), single or bilateral lung transplant (54, 34%), or combination lung and heart transplant (8, 5%). Transplant coordinators reported an increase in patient understanding of their disease and emotional closure related to the disease through the On My Path program. Conclusions.— Pathologists providing direct patient care is a feasible model that addresses currently unmet desires of the transplant population to better understand their pathology. Providing a 3-dimensional model helps to empower patients and drives satisfaction. These interactions also improve awareness about pathology as a discipline and its importance in the continued care of transplant recipients.

Prognostic stratification of pulmonary carcinoids into “typical” and “atypical” categories requires examination of large tissue volume. However, there is a need for tools that provide similar prognostic information on small biopsy samples. Ki-67 and OTP immunohistochemistry have shown promising prognostic value in studies of resected pulmonary carcinoids, but prognostic value when using biopsy/cytology specimens is unclear. Ki-67 immunohistochemistry was performed on small biopsy/cytology specimens from pulmonary carcinoid tumors (n=139), and labeling index was scored via automated image analysis of at least 500 cells. OTP immunohistochemistry was performed on 70 cases with sufficient tissue and scored as positive or negative (<20% tumor nuclei staining). Higher Ki-67 index was associated with worse disease-specific progression-free survival (ds-PFS), with 3% and 4% thresholds having similarly strong associations with ds-PFS ( P <0.001, hazard ratio ≥11). Three-year ds-PFS was 98% for patients with Ki-67 <3% and 89% for patients with Ki-67≥3% ( P =0.0006). The optimal Ki-67 threshold for prediction of typical versus atypical carcinoid histology on subsequent resection was 3.21 (AUC 0.68). Negative OTP staining approached significance with atypical carcinoid histology ( P =0.06) but not with ds-PFS ( P =0.24, hazard ratio=3.45), although sample size was limited. We propose that Ki-67 immunohistochemistry may contribute to risk stratification for carcinoid tumor patients based on small biopsy samples. Identification of a 3% hot-spot Ki-67 threshold as optimal for prediction of ds-PFS is notable as a 3% Ki-67 threshold is currently used for gastrointestinal neuroendocrine tumor stratification, allowing consideration of a unified classification system across organ systems.

Primary pulmonary myxoid sarcoma (PPMS) and thoracic angiomatoid fibrous histiocytoma (AFH) are rare neoplasms with EWSR1 fusions and overlapping morphology. Both tumor types often show epithelial membrane antigen expression, but AFH characteristically co-expresses desmin. We encountered a case of PPMS with the unexpected finding of patchy, strong anaplastic lymphoma kinase (ALK) (previously reported in AFH) and synaptophysin expression. We evaluated a cohort of PPMS and thoracic AFH with systematic morphologic comparison and surveyed for aberrant expression of ALK and synaptophysin. Medical records and slides were reviewed for 16 molecularly confirmed cases of PPMS (n=5) and thoracic AFH (n=11). Each case was scored for morphologic characteristics typical of PPMS and/or AFH. ALK, synaptophysin, chromogranin, desmin, and epithelial membrane antigen immunostains were performed on cases with available tissue. AFH and PPMS cases showed similar age at presentation and long-term tumor behavior. Almost all cases of PPMS and AFH had a fibrous pseudocapsule and lymphoid rim. All PPMS had myxoid stroma and reticular growth pattern, but these features were also present in a subset of AFH. Synaptophysin expression was present in 6 of 11 AFH and 1 of 5 PPMS; all tested cases were negative for chromogranin (n=15). One case of AFH and 1 case of PPMS showed focally strong coexpression of synaptophysin and ALK. AFH and PPMS show considerable clinicopathologic overlap. When supportive, the immunohistochemical findings described may aid in diagnosis before molecular confirmation. PPMS and AFH may be morphologic variants of the same clinicopathologic entity, which can show more immunophenotypic variability than previously reported.

Context.— Primary thoracic neoplasms are rare in children, whereas nonneoplastic mass lesions or cysts and metastases are more common, and there is a relative paucity of comprehensive histopathologic and molecular data. Objective.— To define the clinicopathologic spectrum of neoplastic and nonneoplastic diseases observed in resected mass lesions in the chest of pediatric patients, and to identify somatic alterations observed in primary neoplasms. Design.— Clinicopathologic features of thoracic mass lesions (n = 385) resected from 373 patients aged ≤21 years in a 25-year period (1993–2018) were included. Primary neoplasms having sufficient material were tested by a laboratory-developed comprehensive genomic profiling assay that assesses tumor mutational burden, microsatellite instability, somatic sequence variants, gene amplifications, fusions, and specific transcript variants. Results.— The most commonly resected space-occupying lesions were nonneoplastic mass lesions and cysts or malformations, resected in 117 (31.4%) and 58 of 373 patients (15.5%) respectively. Metastatic neoplasms were observed in 169 of 373 patients (45.3%; mean age 14.4 years, range 1–21 years); the most common was osteosarcoma (68 of 169; 40.2% of metastases). Primary lung neoplasms occurred in 24 of 373 patients (6.4%; mean age 14.5 years, range 6 months–21 years), and 16 patients had primary extrapulmonary thoracic tumors. Carcinoid tumor was the most common primary lung neoplasm (7 typical, 3 atypical). Molecular testing showed a prevalence of somatic pathogenic or likely pathogenic mutations and copy-number alterations. No fusions or splice variants were identified. Tumors were microsatellite-stable with low tumor mutational burden. Conclusions.— Resected pediatric thoracic mass lesions are more likely to be metastatic lesions, congenital cysts or malformations, or nonneoplastic lesions compared to primary thoracic neoplasms, which are encountered at a low frequency and tend to have relatively simple genetic profiles.

Context.— Nuclear protein in testis (NUT) carcinoma is an aggressive carcinoma defined by NUTM1 gene rearrangement. Diagnostic challenges include morphologic overlap with poorly differentiated squamous cell carcinoma, small cell carcinoma, thoracic SMARCA4-deficient undifferentiated tumor, and other small round blue cell tumors. Objective.— To comprehensively study the immunohistochemistry (IHC) features of a large cohort of NUT carcinomas. Design.— Fifty-seven NUT carcinoma cases were identified from 2012–2022, including 38 thoracic/mediastinal, 13 head and neck/sinonasal, and 6 from other sites. Pathology reports and available slides were reviewed. Comprehensive IHC studies were performed on available cases. Results.— Keratin stains showed variable positivity and were entirely negative in 15% (8 of 55) of cases. p40 was only positive in 65% (24 of 37) of cases, implying inferior sensitivity when compared to p63 (87% sensitivity, 20 of 23 cases) and other squamous cell markers. Neuroendocrine markers were focally/weakly positive in few cases; however, INSM1 was positive in 54% (7 of 13) of cases, indicating a possible diagnostic pitfall. TTF-1 was mostly negative with focal positivity in 26% (10 of 38) of cases. Occasional CD34 (15%, 3 of 20 cases) and CD99 (21%, 3 of 14 cases) positivity could also cause potential diagnostic confusion. S100, desmin, CD45, and SALL4 were rarely positive. BRG1 and INI1 were retained in all cases. Ki-67 proliferative index was high (median, 60%). PD-L1 was negative in all tested cases. Conclusions.— This comprehensive IHC study demonstrates the immunohistochemical spectrum of NUT carcinoma. The findings can help narrow the differential diagnosis and recognize potential pitfalls.

Context.— Respiratory infections complicate lung transplantation and increase the risk of allograft dysfunction. Allograft lungs may have different susceptibilities to infection than native lungs, potentially leading to different disease severity in lungs of single lung transplant recipients (SLTRs). Objective.— To study whether infections affect allograft and native lungs differently in SLTRs but similarly in double LTRs (DLTRs). Design.— Using an institutional database of LTRs, medical records were searched, chest computed tomography studies were systematically reviewed, and histopathologic features were recorded per lung lobe and graded semiquantitatively. A multilobar-histopathology score (MLHS) including histopathologic data from each lung and a bilateral ratio (MLHSratio) comparing histopathologies between both lungs were calculated in SLTRs and compared to DLTRs. Results.— Six SLTRs died of infection involving the lungs. All allografts showed multifocal histopathologic evidence of infection, but at least 1 lobe of the native lung was uninvolved. In 4 of 5 DLTRs, histopathologic evidence of infection was seen in all lung lobes. On computed tomography, multifocal ground-glass and/or nodular opacities were found in a bilateral distribution in all DLTRs but in only 2 of 6 SLTRs. In SLTRs, the MLHSAllograft was higher than MLHSNative (P = .02). The MLHSratio values of SLTR and DLTR were significantly different (P &lt; .001). Conclusions.— Allograft and native lungs appear to harbor different susceptibilities to infections. The results are important for the management of LTRs.