A Novel Artificial Intelligence-Based Parameterization Approach of the Stromal Landscape in Merkel Cell Carcinoma: A Multi-Institutional Study.

Tumor-stroma ratio (TSR) has been recognized as a valuable prognostic indicator in various solid tumors. This study aimed to examine the clinicopathologic relevance of TSR in Merkel cell carcinoma (MCC) using artificial intelligence (AI)-based parameterization of the stromal landscape and validate TSR scores generated by our AI model against those assessed by humans. One hundred twelve MCC cases with whole-slide images were collected from 4 different institutions. Whole-slide images were first partitioned into 128 × 128-pixel "mini-patches," then classified using a novel framework, termed pre-tumor and stroma (Pre-TOAST) and TOAST, whose output equaled the probability of the minipatch representing tumor cells rather than stroma. Hierarchical random samplings of 50 minipatches per region were performed throughout 50 regions per slide. TSR and tumor-stroma landscape (TSL) parameters were estimated using the maximum-likelihood algorithm. Receiver operating characteristic curves showed that the area under the curve value of Pre-TOAST in discriminating classes of interest including tumor cells, collagenous stroma, and lymphocytes from nonclasses of interest including hemorrhage, space, and necrosis was 1.00. The area under the curve value of TOAST in differentiating tumor cells from related stroma was 0.93. MCC stroma was categorized into TSR high (TSR ≥ 50%) and TSR low (TSR < 50%) using both AI- and human pathology-based methods. The AI-based TSR-high subgroup exhibited notably shorter metastasis-free survival (MFS) with a statistical significance of P = .029. Interestingly, pathologist-determined TSR subgroups lacked statistical significance in recurrence-free survival, MFS, and overall survival (P > .05). Density-based spatial clustering of applications with noise analysis identified the following 2 distinct TSL clusters: TSL1 and TSL2. TSL2 showed significantly shorter recurrence-free survival (P = .045) and markedly reduced MFS (P < .001) compared with TSL1. TSL classification appears to offer better prognostic discrimination than traditional TSR evaluation in MCC. TSL can be reliably calculated using an AI-based classification framework and predict various prognostic features of MCC.

Elevated Intraocular Pressure in Periorbital Sweet's Syndrome.

A 66-year-old immunocompromised man presented with cellulitis around the left eye that was initially concerning for necrotizing fasciitis. Exam findings were remarkable for exquisite periocular tenderness with rigid, immobile eyelids resulting from severe erythema, edema, and induration. Given the concern for orbital compartment syndrome and a necrotizing infection, the patient was taken urgently to the operating room for debridement of the eyelid skin as well as an urgent lateral canthotomy and cantholysis. His eye exam revealed 360° of hemorrhagic chemosis, no relative afferent pupillary defect, and an ipsilateral elevated intraocular pressure of 35 mm Hg. No visual acuity measurement could be obtained secondary to the patient's altered mental status. His intraocular pressure normalized after treatment with antihypertensive drops and further extension of the canthotomy. Histopathological analysis showed extensive neutrophilic infiltrate of the dermis which was compatible with a diagnosis of Sweet's syndrome.

Stimulant use in patients presenting with psychocutaneous disorders.

BACKGROUND: Psychocutaneous disorders are often attributed to stimulant medications, yet this relationship has never been fully elucidated. Literature on psychocutaneous disorders largely focuses on clinical presentation and treatment rather than disease etiology or exacerbation. OBJECTIVE: To determine whether patients presenting with psychocutaneous disorders display high rates of stimulant use and psychiatric comorbidity. METHODS: We undertook a retrospective cohort study of patients with psychocutaneous disorders presenting to a single center. It was hypothesized that these patients would have high rates of stimulant use and psychiatric comorbidity. Following analysis of baseline demographics, the patients were assigned to 1 of 2 groups: those with a psychotic disorder and those with a neurotic disorder. RESULTS: Sixty percent of the patients (n = 317) with psychocutaneous disease had recently used a stimulant and more than 80% (270 of 317) carried an additional psychiatric diagnosis. The neurotic disorder group (n = 237) was younger and had higher rates of stimulant use. The psychotic disorder group (n = 80) had higher rates of psychosis, medical comorbidity, and illicit stimulant drug use. LIMITATIONS: The predominantly Caucasian population may limit generalizability of findings as may the retrospective nature. CONCLUSIONS: Patients with psychocutaneous disease have high rates of stimulant use and most have at least 1 psychiatric comorbidity.

Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion and prominent epidermal involvement: A case report.

Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMCT) is a recently described entity with only 13 cases reported in the literature. Histopathologically, the neoplasm consists of atypical epithelioid to spindled cells that form a well-circumscribed nodule usually confined to the dermis and subcutis with cytological features including large vesicular nuclei with prominent nucleoli and abundant eosinophilic cytoplasm. Immunohistochemistry shows variable expressivity of melanocytic markers. Currently, there are limited data regarding long-term outcomes of this newly described entity. Most cases have done well, but there is one case reported with an adverse event. Hence, further studies are needed to accurately classify this tumor. Definitive diagnosis is made by laboratory evidence of CMCT. Herein, we report the first case of CMCT with epidermal involvement in the youngest patient known to be affected to date.

Skeletal muscle regeneration in post-myofascial flap reconstruction specimens mimicking sarcoma: A potential diagnostic pitfall.

Skeletal muscle regeneration (SMR) encompasses a sequence of events that unfolds after injury to muscle fibers. Nearby satellite cells become activated and function as precursor muscle cells by proliferating and differentiating into myoblasts, which eventually fuse to form myotubes and ultimately mature muscle fibers. Compared to other forms of mesenchymal repair, SMR has higher morphologic heterogeneity with the potential to show histopathologic similarities to sarcomas and other malignancies. It is important to recognize SMR and settings in which this can occur to avoid misdiagnosis. We report two cases where a diagnosis of SMR was made from tissue taken from locations previously treated with Mohs micrographic surgery followed by myofascial flap reconstruction. In both cases, histopathologic features identified with hematoxylin and eosin as well as immunostaining were used to support the diagnosis of SMR. These cases highlight the importance of recognizing this clinic entity to ensure accurate diagnosis.

Appropriate use criteria in dermatopathology: Initial recommendations from the American Society of Dermatopathology.

BACKGROUND: Appropriate use criteria (AUC) provide physicians guidance in test selection, and can affect health care delivery, reimbursement policy, and physician decision-making. OBJECTIVES: The American Society of Dermatopathology, with input from the American Academy of Dermatology and the College of American Pathologists, sought to develop AUC in dermatopathology. METHODS: The RAND/UCLA appropriateness methodology, which combines evidence-based medicine, clinical experience, and expert judgment, was used to develop AUC in dermatopathology. RESULTS: With the number of ratings predetermined at 3, AUC were developed for 211 clinical scenarios involving 12 ancillary studies. Consensus was reached for 188 (89%) clinical scenarios, with 93 (44%) considered "usually appropriate" and 52 (25%) "rarely appropriate" and 43 (20%) having "uncertain appropriateness." LIMITATIONS: The methodology requires a focus on appropriateness without comparison between tests and irrespective of cost. CONCLUSIONS: The ultimate decision to order specific tests rests with the physician and is one where the expected benefit exceeds the negative consequences. This publication outlines the recommendations of appropriateness-the AUC for 12 tests used in dermatopathology. Importantly, these recommendations may change considering new evidence. Results deemed "uncertain appropriateness" and where consensus was not reached may benefit from further research.

Dermal elastolysis in the setting of combination immunotherapy.

Multiple cutaneous side effects have been reported with the use of immunotherapies including programmed cell death protein 1 inhibitors. We report 2 patients who presented with papillary dermal elastolysis presenting as multiple, skin-colored, wrinkled papules and atrophic macules following an inflammatory eruption in the setting of combination chemotherapy with nivolumab and cabiralizumab. These two cases highlight a novel finding, elastolysis in the setting of chemotherapy with nivolumab and cabiralizumab.

Appropriate use criteria in dermatopathology: Initial recommendations from the American Society of Dermatopathology.

BACKGROUND: Appropriate use criteria (AUC) provide physicians guidance in test selection, and can affect health care delivery, reimbursement policy and physician decision-making. OBJECTIVES: The American Society of Dermatopathology, with input from the American Academy of Dermatology and the College of American Pathologists, sought to develop AUC in dermatopathology. METHODS: The RAND/UCLA appropriateness methodology, which combines evidence-based medicine, clinical experience and expert judgment, was used to develop AUC in dermatopathology. RESULTS: With the number of ratings predetermined at 3, AUC were developed for 211 clinical scenarios involving 12 ancillary studies. Consensus was reached for 188 (89%) clinical scenarios, with 93 (44%) considered "usually appropriate," 52 (25%) "rarely appropriate" and 43 (20%) "uncertain appropriateness." LIMITATIONS: The methodology requires a focus on appropriateness without comparison between tests and irrespective of cost. CONCLUSIONS: The ultimate decision of when to order specific test rests with the physician and is one where the expected benefit exceeds the negative consequences. This publication outlines the recommendations of appropriateness-AUC for 12 tests used in dermatopathology. Importantly, these recommendations may change considering new evidence. Results deemed "uncertain appropriateness" and where consensus was not reached may benefit from further research.

Urethral lichen sclerosus under the microscope: a survey of academic pathologists.

INTRODUCTION: Given the poor understanding of the pathophysiology of genital lichen sclerosus (GLS) and a lack of accepted definitive diagnostic criteria, we proposed to survey pathologists regarding their understanding of GLS. We hypothesized that significant disagreement about GLS will exist. MATERIALS AND METHODS: All urologists participating in the Trauma and Urologic Reconstruction Network of Surgeons identified genitourinary (GUP) and dermatopathologists (DP) at their respective institutions who were then invited to participate in an online survey regarding their experience with diagnosing GLS, GLS pathophysiology and its relationship to urethral stricture disease. RESULTS: There were 23 (12 DP, 11 GUP) pathologists that completed the survey. The most agreed upon criteria for diagnosis were dermal collagen homogenization (85.7%), loss of the normal rete pattern (33.3%) and atrophic epidermis (28.5%). No pathologists believed GLS had an infectious etiology (19% maybe, 42% unknown) and 19% believed GLS to be an autoimmune disorder (42% maybe, 38% unknown); 19% believed LS to be premalignant, but 52% believed it was associated with cancer; 80% believed that LS could involve the urethra (DP (92%) versus GUP (67%); p = 0.272). Of those diagnosing urethral GLS, 80% of DUP believed that GLS must first involve the glans/prepuce before involving the urethra, while all GUP believed that urethral disease could exist in isolation (p = 0.007). CONCLUSIONS: There was significant disagreement in this specialized cohort of pathologists when diagnosing GLS. A logical first step appears to be improving agreement on how to best describe and classify the disease. This may lead to improve treatments.

Follicular lymphomatoid papulosis with follicular mucinosis: a clinicopathologic study of 3 cases with literature review and conceptual reappraisal.

Lymphomatoid papulosis (LyP), characterized by recurring, waxing and waning, cutaneous papulonodules, is increasingly recognized to represent a heterogeneous collection of pathologically dissimilar subtypes. Recently, a follicular LyP variant was proposed, featuring folliculotropism. Folliculotropism by atypical lymphocytes is conventionally associated with follicular mucinosis and mycosis fungoides (MF), and review of the literature suggests co-occurrence of folliculotropism and follicular mucinosis in LyP to be rare, with only 3 cases identified to date. Herein we describe 3 additional cases, each manifesting a typical LyP clinical picture, with the additional element of folliculotropism and follicular mucinosis on pathology. These cases suggest that LyP should be considered alongside MF in the differential diagnosis of follicular mucinosis with accompanying atypical lymphocytic infiltration. As LyP can occur with other lymphoproliferative disorders such as MF, the finding of follicular mucinosis in LyP may further represent a conceptual intersection between the 2 disease processes.

Cutaneous metastasis of breast adenoid cystic carcinoma to the scalp.

Adenoid cystic carcinoma (ACC) is a tumor that can be of primary cutaneous origin or secondary to metastatic disease, most commonly salivary origin. Aside from primary cutaneous and salivary types, ACC of the breast is a rare, more indolent variant. Cutaneous metastases secondary to breast ACC is exceedingly uncommon and not previously reported to our knowledge. We present the case of a 67-year-old woman who developed cutaneous metastasis from primary breast ACC.

Eosinophils in biopsy specimens of lichen sclerosus: a not uncommon finding.

BACKGROUND: Evolving lesions of lichen sclerosus (LS) pose a diagnostic challenge owing to an absence of classic findings of epidermal atrophy, dermal sclerosis, a band-like lymphocytic infiltrate and the presence of eosinophils. METHODS: Retrospective specimens of LS were reviewed. Demographic information, biopsy vs. excision and the following histopathological characteristics were noted: presence and number of eosinophils, epidermal hyperplasia, spongiosis, early/transitional LS, well-developed LS and coexisting squamous cell carcinoma (SCC). Linear regression analysis was performed. RESULTS: The data consisted of 66 biopsies (36 male [M], 30 female [F]), from 53 individuals (33M, 20F), including 57 genital and 9 extragenital biopsies. Seven biopsies showed SCC, 28 showed epidermal hyperplasia and 14 exhibited spongiosis. Thirty-five specimens were early/transitional LS and commonly exhibited epidermal hyperplasia (57%), epidermotropism of lymphocytes (97%) and basement membrane thickening (97%). Thirty-five biopsies (53%) contained eosinophils (23 early/transitional lesions). Male gender (p = 0.074) was associated with increased eosinophils. The presence of SCC (p = 0.014) was a significant predictors of eosinophil number. CONCLUSIONS: Epidermal hyperplasia, epidermotropism of lymphocytes and basement membrane thickening are helpful features in identifying early LS. Eosinophils are not an uncommon finding in LS and are most common in male genital lesions and in LS associated with SCC.

Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.

Herein, we describe a 63-year-old male with multiple tumors arising within a nevus sebaceus on the posterior scalp. On histopathologic examination, four distinct tumors were identified: trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum (TFI). Within the TFI component of the nevus sebaceus, there was intracytoplasmic accumulation of eosinophilic keratin, as shown on pancytokeratin-stained sections, imparting a signet-ring appearance to the cells. To our knowledge, this is the first report of signet-ring cells arising within a TFI occurring in a nevus sebaceus. We discuss this case as well as review the literature on multiple tumors arising within nevus sebaceus and signet-ring cell changes in primary cutaneous tumors.

Ulcerated Spitz nevus masquerading as a juvenile xanthogranuloma.

We report a case of ulcerated atypical Spitz nevi that demonstrated a yellow to light orange background under dermoscopy, which can be seen in juvenile xanthogranuloma (JXG) and is referred to as the "setting sun" appearance. This yellow to orange appearance was due to serous crusting and not histiocytic infiltration, which is seen in JXG. This case highlights overlapping dermatoscopic features between the two skin lesions and polymorphous vascular structures, which are unique to atypical Spitz nevi.

Nodular secondary syphilis with associated granulomatous inflammation: case report and literature review.

A 62-year-old male presented with a 10-day history of a diffuse, erythematous papular rash sparing the palms and soles. Histopathologic examination of a skin lesion showed loose non-caseating granulomas in a lymphoplasmacytic background. Scattered spirochetes were identified by Treponema pallidum immunohistochemistry, in keeping with a diagnosis of secondary syphilis. Granulomatous inflammation in secondary syphilis is uncommon. A review of the literature reveals that the majority of prior reported cases of granulomatous secondary syphilis share similar characteristics to this case; namely, a papular or nodular clinical presentation, sparing of the palms and soles, and collections of epithelioid histiocytes with associated lymphocytes and variable numbers of plasma cells.

Histiocytoid Sweet syndrome with haloed myeloid cells masquerading as a cryptococcal infection.

: Histiocytoid Sweet syndrome is a histopathologic variant of Sweet syndrome characterized by an infiltrate of mononuclear cells that have a histiocytic appearance and represent immature granulocytes. The primary histopathologic differential diagnosis for histiocytoid Sweet syndrome includes leukemia cutis and true histiocytic dermatoses. However, it does not usually include a deep mycotic infection. Herein, we describe a case of histiocytoid Sweet syndrome in a 75-year-old man in which histopathologic examination showed a dense dermal infiltrate composed of mature neutrophils and numerous yeast-like mononuclear cells with a surrounding halo, suspicious for cryptococcal organisms. Immunohistochemical and histochemical studies demonstrated expression of myeloperoxidase by the yeast-like forms and an absence of periodic acid-Schiff and mucicarmine staining. Microbiologic culture studies were negative for fungal organisms. The case met all the criteria for Sweet syndrome and, given the cytomorphology of the mononuclear cells with vesicular irregularly rounded nuclei and myeloperoxidase expression, the case was most consistent with histiocytoid Sweet syndrome. The perinuclear haloes in this case most likely represent cytoplasmic vacuolization of the immature, histiocytoid appearing neutrophils secondary to a novel nonapoptotic caspase-independent death pathway. This case highlights the histopathologic similarities that may be present between cryptococcal infection and histiocytoid Sweet syndrome, and the utility of immunohistochemical markers and histochemical staining to differentiate between the two entities.

Specific analysis of KIT and PDGFR-alpha expression and mutational status in Merkel cell carcinoma.

BACKGROUND: The purpose of this study was to explore the immunohistochemical and mutational status of the tyrosine kinases KIT and platelet derived growth receptor-alpha (PDGFRA) in Merkel cell carcinoma (MCC). Specifically, we examined the mutated exons in gastrointestinal stromal cell tumors that may confer a treatment response to imatinib mesylate. METHODS: We evaluated KIT and PDGFRA immunostaining in 23 examples of MCC utilizing laser capture microdissection to obtain pure samples of tumor genomic DNA from 18 of 23 examples of MCC. PCR amplification and sequencing of KIT exons 9, 11, 13 and 17, and PDGFRA exons 10, 12, 14 and 18 for mutations was performed. RESULTS: Fifteen of 23 tumors (65%) demonstrated CD117 expression and 22 of 23 tumors (95%) demonstrated PDGFRA expression. A single heterozygous KIT exon 11 base change resulting in an E583K mutation was discovered in 12 of 18 (66%) examples of MCC. In addition, a single nucleotide polymorphism was detected in eight of 18 tumors (44%) in exon 18 of PDGFRA (codon 824; GTC > GTT). CONCLUSIONS: We discovered a novel somatic KIT exon 11 E583K mutation in 66% of tumors. This mutation has been previously described in a human with piebaldism and appears to represent an inactivating mutation. Therefore, despite expression of CD117 and PDGFRA, the absence of activating mutations in these tyrosine kinases makes KIT and PDGFRA unlikely candidates of MCC oncogenesis.

Nonuremic calciphylaxis associated with histologic changes of pseudoxanthoma elasticum.

Calciphylaxis is a rare condition characterized by medial calcification of small- and medium-sized vessels that subsequently leads to ischemic necrosis. Calciphylaxis most often occurs in patients with end-stage renal disease and secondary hyperparathyroidism. We present a unique case of calciphylaxis in which the patient did not have end-stage renal disease. Instead, primary hyperparathyroidism and/or alcoholic cirrhosis were the more likely causes of her calciphylaxis. In addition, our case demonstrated not only calciphylaxis but also fragmentation and calcification of elastic fibers within the dermis, changes that are most often seen in pseudoxanthoma elasticum. This is the first reported case of calciphylaxis, to our knowledge, with histopathologic changes of pseudoxanthoma elasticum in a patient who is nonuremic.

Acute mucocutaneous methotrexate toxicity associated with interface dermatitis and numerous eosinophils.

Acute mucocutaneous methotrexate toxicity is not classically associated with prominent tissue eosinophilia. We present a case of acute methotrexate toxicity associated with pancytopenia and mucocutaneous erosion with interface dermatitis and numerous eosinophils. A 79-year-old male, with a history of psoriasis vulgaris on methotrexate therapy, presented with blisters of the oral mucosa, groin, sacrum, and extremities after daily consumption of methotrexate. Examination revealed blisters and erosions localized to psoriatic plaques, the perineum, and the oral mucosa. Laboratory evaluation demonstrated pancytopenia, megaloblastic anemia, and elevated liver function tests. A skin biopsy of an eroded plaque revealed psoriasiform epidermal hyperplasia with epidermal erosion, parakeratosis, and loss of the granular cell layer. There was an underlying band-like lymphoid infiltrate with interface dermatitis, dyskeratotic keratinocytes, and numerous eosinophils. Direct immunofluorescence studies were negative for the deposition of immunoreactants. Methotrexate was held, and the patient received leucovorin resulting in improvement of blood counts and cutaneous lesions. The histopathologic changes associated with acute mucocutaneous toxicity have been described as pauci-inflammatory erosions associated with dyskeratotic keratinocytes to interface dermatitis with necrotic keratinocytes and occasionally associated eosinophils. Although these changes are most often superimposed on psoriatic plaques, they have been reported to occur on normal skin. Therefore, the differential diagnosis may include lichen planus, a lichenoid drug eruption, or a fixed drug eruption, and given the presence of mucosal ulceration, incipient pemphigus vulgaris or paraneoplastic pemphigus vulgaris. This case illustrates that acute mucocutaneous methotrexate toxicity may be associated with both interface dermatitis and numerous eosinophils.