Assessment of Mammalian Target of Rapamycin Pathway Activation in Basal Cell Carcinoma as a New Therapeutic Approach.

ABSTRACT: Targeting the mammalian target of rapamycin (mTOR) pathway represents a potentially novel approach to treat basal cell carcinoma (BCC), but activation of this pathway has not been well described in human BCCs. The purpose of this study was to assess whether mTOR pathway activation occurs in BCCs (both sporadic and syndromic) and report a case of a patient with Gorlin syndrome (GS) whose clinically suspicious BCCs responded to mTOR inhibition through topical sirolimus treatment. After Stanford Institutional Review Board Approval, archived BCCs from patients with GS (n = 25), sporadic BCCs (n = 35), and control tissues were subjected to immunohistochemical analysis for the activation of mTOR pathway, and immunohistochemical staining intensity was evaluated by a dermatopathologist. BCCs (compared with normal skin) had elevated levels of eIF4EBP1 (Padjusted = 0.0336), which is downstream of mTOR. a serine/threonine kinase Phospho-(AKT), which interacts with mTOR, was also significantly elevated (perinuclear: Padjusted < 0.0001; cytoplasmic: Padjusted = 0.0021). When off-label topical 1% sirolimus was used on a pediatric patient with GS, we noted reduction of new BCC development and decreased size of existing neoplasms clinically suspicious for BCCs. This treatment was well tolerated after 2 years of continuous use, with no other treatments needed during this period. Topical sirolimus is a promising therapeutic candidate against both sporadic and GS-associated BCC. Multicenter, prospective studies are needed to understand the efficacy and safety of topical mTOR inhibitors in BCC treatment, and ascertain whether the immunohistochemical markers downstream of mTOR could have predictive value in identifying BCCs most likely to respond to topical mTOR inhibitors, such as sirolimus.

Randomized Controlled Trial Investigating Cold Snare and Forceps Polypectomy Among Small POLYPs in Rates of Complete Resection: The TINYPOLYP Trial.

INTRODUCTION: Optimizing complete resection during colonoscopy is important because residual neoplastic tissue may play a role in interval cancers. The US Multi-Society Task Force recommends diminutive (≤5 mm) and small (6-9 mm) polyps be removed by cold snare polypectomy (CSP). However, evidence is less clear whether CSP retains significant advantage over cold forceps polypectomy (CFP) for polyps ≤3 mm. METHODS: This study is a single-center prospective noninferiority randomized clinical trial evaluating CFP and CSP for nonpedunculated polyps ≤3 mm. Patients 18 years and older undergoing colonoscopy for any indication were recruited. During each colonoscopy, polyps underwent block randomization to removal with CFP or CSP. After polypectomy, 2 biopsies were taken from the polypectomy margin. The primary noninferiority outcome was the complete resection rate, defined by absence of residual polyp in the margin biopsies. RESULTS: A total of 179 patients were included. Patients had similar distribution in age, sex, race/ethnicity, as well as indication of procedure. A total of 279 polyps ≤3 mm were identified, with 138 in the CSP group and 141 in the CFP group. Mean polypectomy time was longer for CSP compared with CFP (42.3 vs 23.2 seconds, P < 0.001), although a higher proportion of polyps removed by CFP were removed in more than 1 piece compared with CSP (15.6 vs 3.6%, P < 0.001). There were positive margin biopsies in 2 cases per cohort, with a complete resection rate of 98.3% in both groups. There was no significant difference in cohorts in complete resection rates (difference in complete resection rates was 0.057%, 95% confidence interval: -4.30% to 4.53%), demonstrating noninferiority of CFP compared with CSP. DISCUSSION: Use of CFP was noninferior to CSP in the complete resection of nonpedunculated polyps ≤3 mm. CSP required significantly more time to perform compared with CFP. CFP should be considered an acceptable alternative to CSP for removal of polyps ≤3 mm.

Randomized controlled trial investigating use of submucosal injection of EverLift™ in rates of complete resection of non-pedunculated 4-9 mm polyps.

INTRODUCTION: Currently, cold snare polypectomy (CSP) without submucosal injection is recommended for removing polyps < 10 mm. Use of viscous submucosal agents has not been previously evaluated in CSP. We investigate the potential role of EverLift™ (GI Supply, Pennsylvania) in CSP. METHODS: The study is a single-center prospective randomized non-inferiority clinical trial evaluating CSP of non-pedunculated 4-9 mm polyps, with or without submucosal injection of EverLift™. Patients 18-80 years of age presenting for colonoscopy were recruited. Eligible polyps underwent block randomization to CSP with or without EverLift™. Following CSP, two biopsies were performed at the CSP site margin. The primary non-inferiority outcome was complete resection rate, defined by absence of residual polyp in the margin biopsies (non-inferiority margin -10%). RESULTS: A total of 291 eligible polyps underwent CSP, with 142 removed using EverLift™. There was similar polyp size and distribution of pathology between the two groups. Overall, there was a low rate of positive margins with (1.4%) or without submucosal injection (2.8%), with no significant difference in complete resection (difference 1.28%, 95% CI: -2.66 to 5.42%), demonstrating non-inferiority of EverLift™ injection. Use of EverLift™ significantly increased CSP time (109.8 vs 38.8 s, p < 0.0001) and frequency of use of hemostatic clips (13.4 vs 3.6%, p = 0.002). CONCLUSION: Submucosal injection of EverLift™ was non-inferior to CSP of 4-9 mm polyps without injection and increased time for resection as well as use of hemostatic clips to control acute bleeding. Our results suggest that polypectomy of 4-9 mm polyps can be safely performed without submucosal injection of EverLift™.

Spitz nevus with EHBP1-ALK fusion and distinctive membranous localization of ALK.

ALK rearrangements define a histopathologically distinctive yet diverse subset of Spitz tumors characterized by fusiform to epithelioid melanocytes with frequent fascicular growth and ALK overexpression. Molecularly, these tumors are characterized by fusions between ALK and a variety of gene partners, most commonly TPM3 and DCTN1. We describe an unusual case of a Spitz nevus occurring in a 13-year-old female that manifested ALK immunopositivity with cell membrane localization. The proliferation was polypoid and composed of elongated nests of epithelioid melanocytes with enlarged nuclei, prominent nucleoli, and abundant cytoplasm without significant atypia and lacking mitotic figures. The nevus exhibited strong and diffuse expression of p16. Targeted next-generation RNA sequencing revealed an in-frame EHBP1-ALK fusion, which has been reported only once in the literature. EHBP1 encodes an adaptor protein with plasma membrane targeting potential. Together, these findings suggest that the 5' ALK fusion partner in Spitz tumors may dictate the subcellular localization of the ALK chimeric oncoprotein. In summary, this case highlights a rare ALK fusion associated with a distinct immunohistochemical staining pattern and further expands the spectrum of ALK-rearranged melanocytic tumors.

Next-generation sequencing confirms T-cell clonality in a subset of pediatric pityriasis lichenoides.

BACKGROUND: Pityriasis lichenoides (PL) is a papulosquamous disease that affects both adults and children. Previous studies have shown a subset of this entity to have clonal T-cell populations via PCR-based assays. In this study, we sought to implement next-generation sequencing (NGS) as a more sensitive and specific test to examine for T-cell clonality within the pediatric population. METHODS: We identified 18 biopsy specimens from 12 pediatric patients with clinical and histopathologic findings compatible with PL. Patient demographics, clinical features, management, and histopathologic findings were reviewed. All specimens were analyzed for clonality with NGS of T-cell receptor beta (TRB) and gamma (TRG) genes. RESULTS: Of the 12 patients, 9 (75%) had complete resolution of lesions at the time of data collection (mean follow-up 31 months). The remaining three patients significantly improved with methotrexate (with or without acitretin). Interestingly, 7 of 12 patients (58%) and 9 of 17 biopsy specimens (53%) showed evidence of T-cell clonality. Two patients showed matching TRB clones from different anatomic sites. CONCLUSIONS: T-cell clonality is a common finding in PL, probably representing a "reactive clonality" rather than a true lymphoproliferative disorder. Clonality alone cannot be used as a means to distinguish PL from lymphomatoid papulosis or cutaneous lymphoma.

Immunohistochemical and molecular updates in cutaneous soft tissue neoplasms.

Accurate classification of soft tissue neoplasms of the skin and subcutis can be challenging given the sometimes significant histomorphologic and immunohistochemical overlap between the entities that comprise this ever-expanding category of tumors. With the benefit of continually emerging adjuncts to histologic diagnosis, pathologists have a number of tools at their disposal for navigating this group of neoplasms. This article aims to review recent immunohistochemical and molecular updates in the diagnosis of cutaneous soft tissue neoplasms.

Nodular fasciitis of the breast: clinicopathologic and molecular characterization with identification of novel USP6 fusion partners.

Nodular fasciitis is a benign, self-limited, pseudosarcomatous neoplasm that can mimic malignancy due to its rapid growth, cellularity, and mitotic activity. Involvement of the breast is rare and diagnosis on biopsy can be challenging. In this largest series to date, we examined the clinicopathologic and molecular characteristics of 12 cases of nodular fasciitis involving the breast/axilla. All patients were female, with a median age of 32 years (range 15-61). The lesions were 0.4 to 5.8 cm in size (median 0.8). All cases presented as palpable masses, and two patients had overlying skin retraction. Microscopically, lesions were relatively well-circumscribed nodular masses of bland myofibroblastic spindle cells within a variably myxoid stroma. Infiltrative growth into adipose tissue or breast epithelium was frequent. Mitotic figures were present in all cases, ranging from 1 to 12 per 10 high-power fields (median 3). Immunohistochemically, all cases expressed smooth muscle actin and were negative for pan-cytokeratin, p63, desmin, CD34, and nuclear beta-catenin. Targeted RNA sequencing performed on 11 cases identified USP6 gene fusions in eight; one additional case was positive by break-apart fluorescence in situ hybridization. The common MYH9-USP6 rearrangement was detected in four cases; another case had a rare alternative fusion with CTNNB1. Three cases harbored novel USP6 gene fusions involving NACA, SLFN11, or LDHA. All fusions juxtaposed the promoter region of the 5' partner gene with the full-length coding sequence of USP6. Outcome data were available for eight patients; none developed recurrence or metastasis. Five patients elected for observation without immediate excision, and self-resolution of the lesions was reported in three cases. Albeit uncommon, nodular fasciitis should be considered in the differential diagnosis of breast spindle cell lesions. A broad immunohistochemical panel to exclude histologic mimics, including metaplastic carcinoma, is important. Confirmatory detection of USP6 rearrangements can aid in classification, with potential therapeutic implications.

Cutaneous desmoid-type fibromatosis: A rare case with molecular profiling.

Fibromatoses encompass a broad group of histopathologically similar fibroblastic/myofibroblastic proliferations with divergent clinical manifestations and behavior. Deep (desmoid-type) fibromatoses are typically large, rapidly growing, and locally aggressive tumors that occur in the abdominal wall, mesentery, and extra-abdominal soft tissue, principally the musculature of the trunk and extremities. Most sporadic cases of desmoid fibromatosis harbor inactivating mutations in CTNNB1, the gene encoding beta-catenin. Tumors occurring in the context of familial adenomatous polyposis and Gardner syndrome bear inactivating mutations in APC. By contrast, mutations in CTNNB1 or APC have not been identified in cases of superficial fibromatosis. Cutaneous involvement by desmoid fibromatosis is exceedingly rare. Here we present a 78-year-old male with desmoid-type fibromatosis arising in the dermis of the right medial calf with a pathogenic mutation in CTNNB1 and a variant of unknown significance in APC.

ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism.

Historically recognized by their characteristic histopathologic features, Spitz neoplasms are now known to be molecularly defined by mutually exclusive recurrent abnormalities that cause activation of the MAPK pathway. Spitz neoplasms with ALK rearrangements frequently demonstrate polypoid growth with a plexiform arrangement of nested, fusiform melanocytes in intersecting fascicles. Although neurotropism has been described in indolent Spitz neoplasms, this feature is not frequently mentioned in publications on histopathologic assessment of this group of melanocytic tumors. Here, we present an unusual case of a 3-year-old female with an ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism occurring on the vermilion border of the lower lip.

Immunohistochemical ALK Expression in Granular Cell Atypical Fibroxanthoma: A Diagnostic Pitfall for ALK-Rearranged Non-neural Granular Cell Tumor.

ABSTRACT: Atypical fibroxanthoma (AFX) is a neoplasm that most commonly occurs on sun-damaged skin of the head and neck in elderly patients and that usually exhibits indolent clinical behavior with complete excision. The granular cell variant of AFX demonstrates overlapping histopathologic features with dermal non-neural granular cell tumor (NNGCT), which typically arises on the extremities of young to middle aged adults with rare reports of regional metastasis. A subset of NNGCT harbors ALK rearrangements and expresses ALK by immunohistochemistry. Here, we present 2 cases of granular cell AFX occurring on the scalp of males aged 73 and 87 with ALK expression by immunohistochemistry and no evidence of an ALK rearrangement on fluorescence in situ hybridization, representing a diagnostic pitfall for NNGCT.

Disseminated tuberculosis presenting as medium-vessel vasculitis in an immunocompromised host.

Cutaneous tuberculosis is an uncommon entity with several clinical forms recognized. Histopathologically, most cases are characterized by granulomatous inflammation and caseating necrosis, although less common findings, including vasculitis, have also been described. We report a 55-year-old male with a history of recently diagnosed dermatomyositis receiving immunosuppression with mycophenolate mofetil and prednisone, who developed multifocal soft tissue abscesses and an indurated erythematous plaque on the back. Skin biopsy of the back revealed a necrotizing medium-vessel vasculitis. Mycobacterium tuberculosis was detected in the skin via acid-fast bacilli stain and confirmed by tissue culture and polymerase chain reaction. Cutaneous findings improved rapidly with antituberculosis therapy. This case illustrates an uncommon clinical and histopathologic presentation of disseminated tuberculosis.

PRAME expression in melanocytic proliferations with intermediate histopathologic or spitzoid features.

BACKGROUND: PRAME (PReferentially expressed Antigen in MElanoma) has shown utility in distinguishing melanoma from benign melanocytic lesions, but knowledge of its expression pattern in intermediate melanocytic and spitzoid proliferations is limited. METHODS: Immunohistochemical expression of PRAME was examined in 112 melanocytic proliferations with intermediate histopathologic or spitzoid features. RESULTS: Any intensity of nuclear PRAME staining in at least 60% of lesional melanocytes was determined as the best threshold for diffuse staining in this cohort. Nearly all non-spitzoid melanomas (23/24; 95.8%) demonstrated diffuse PRAME expression. PRAME was completely negative in 95.6% (43/45) of mitotically-active nevi, traumatized nevi, nevi with persistent/recurrent features, and dysplastic nevi. Most Spitz nevi (15/20) and atypical Spitz tumors (10/13) entirely lacked PRAME expression. One Spitz nevus, one atypical Spitz tumor, and one spitzoid melanoma (1/2) demonstrated diffuse PRAME expression. CONCLUSIONS: Although diffuse PRAME expression is generally limited to malignant melanoma, benign Spitz nevi and atypical Spitz tumors can infrequently express diffuse PRAME. PRAME immunohistochemistry can be useful in the evaluation of atypical melanocytic proliferations with intermediate histopathologic features but should be interpreted with caution in the setting of spitzoid neoplasms.

Cutaneous pleomorphic fibromas arising in patients with germline TP53 mutations.

Pleomorphic fibromas are rare benign cutaneous neoplasms associated with deletion/loss of chromosomes 13q and 17p, where RB1 and TP53 are located, respectively. Herein, we report five cases of pleomorphic fibroma arising in patients with germline TP53 mutations, suggesting a potential link with Li-Fraumeni syndrome. All three patients were female and young (mean age 27) with a strong personal and/or family oncologic history and confirmed pathogenic germline TP53 mutations. In two patients, multiple pleomorphic fibromas were diagnosed. Clinically, the lesions arose at various cutaneous sites and were small (≤2 cm) and raised (4/5). Histopathologically, the tumors were paucicellular, composed of atypical spindled to stellate cells with hyperchromatic and variably pleomorphic nuclei. Mitotic activity was exceedingly low, although rare atypical mitotic figures were seen in one case. Immunohistochemically, the tumor cells were diffusely positive for p16 (3/3) and showed loss of Rb expression (5/5). All cases showed aberrant p53 expression (overexpression in 4, complete loss in 1). The tumors have followed a benign clinical course with no evidence of progression or recurrence. In conclusion, the development of multiple pleomorphic fibromas in a young patient may be a clue to an underlying genetic cancer syndrome involving TP53.

Molecular profiling of a primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid.

Primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid is a rare and aggressive neoplasm. Fewer than 50 cases have been reported in the literature, and the genetic driving mutations are unknown. Herein, we present a case of this rare disease along with the results of molecular profiling via targeted next-generation sequencing. The patient is an 85-year-old man who presented with left eyelid swelling initially thought to be a chalazion. After no response to incision and drainage and antibiotics, an incisional biopsy was performed. Histopathologic sections revealed a proliferation of cells with signet-ring and histiocytoid morphology arranged singly and in cords infiltrating the dermis, subcutaneous tissue, and muscle. The lesional cells strongly expressed cytoplasmic cytokeratin 7 and nuclear androgen receptor. Next-generation sequencing revealed a CDH1 mutation, which is known to confer signet-ring morphology in other carcinomas. Pathogenic mutations in NTRK3, CDKN1B, and PIK3CA were also detected. To our knowledge, this is the first documented genetic analysis of this rare disease with findings that offer insights into disease pathogenesis and potential therapeutic targets.

Expression of the transcription factor ZBTB46 distinguishes human histiocytic disorders of classical dendritic cell origin.

Distinguishing classical dendritic cells from other myeloid cell types is complicated by the shared expression of cell surface markers. ZBTB46 is a zinc finger and BTB domain-containing transcription factor, which is expressed by dendritic cells and committed dendritic cell precursors, but not by plasmacytoid dendritic cells, monocytes, macrophages, or other immune cell populations. In this study, we demonstrate that expression of ZBTB46 identifies human dendritic cell neoplasms. We examined ZBTB46 expression in a range of benign and malignant histiocytic disorders and found that ZBTB46 is able to clearly define the dendritic cell identity of many previously unclassified histiocytic disease subtypes. In particular, all examined cases of Langerhans cell histiocytosis and histiocytic sarcoma expressed ZBTB46, while all cases of blastic plasmacytoid dendritic cell neoplasm, chronic myelomonocytic leukemia, juvenile xanthogranuloma, Rosai-Dorfman disease, and Erdheim-Chester disease failed to demonstrate expression of ZBTB46. Moreover, ZBTB46 expression clarified the identity of diagnostically challenging neoplasms, such as cases of indeterminate cell histiocytosis, classifying a fraction of these entities as dendritic cell malignancies. These findings clarify the lineage origins of human histiocytic disorders and distinguish dendritic cell disorders from all other myeloid neoplasms.

Primary cutaneous anaplastic large cell lymphoma.

Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a CD30+ lymphoproliferative disorder (LPD) of the skin with a relatively good prognosis in the absence of high-stage disease. CD30+ LPDs comprise approximately 25%-30% of primary cutaneous lymphomas and as a group represent the second most common clonal T-cell neoplasm of the skin behind mycosis fungoides. Diagnosis of PC-ALCL relies strongly on clinicopathologic correlation given the potential morphologic, clinical and molecular overlap with the other cutaneous CD30+ LPD, lymphomatoid papulosis, and more aggressive hematolymphoid neoplasms.