Clinical and pathological characterization of tebentafusp-associated skin toxicity: A cohort study with 33 patients.

BACKGROUND: Tebentafusp is a novel treatment for patients with metastatic uveal melanoma and often causes cutaneous side effects. OBJECTIVES: The aim of this study was to better characterize these heterogenous cutaneous side effects. METHODS: This prospective cohort study evaluated all patients from a tertiary hospital center who were treated with tebentafusp between January 2019 and June 2023 clinically and assessed skin biopsies histologically. RESULTS: In total, 33 patients were analyzed. Skin toxicity was observed in 78.8% of patients and was classified into 5 clinical categories: (1) symmetrical erythematous patches (83.8%), (2) hemorrhagic macules (11.8%), (3) urticarial lesions (7.4%), (4) bullous lesions (1.5%), and (5) skin (8.5%) and hair depigmentation (11.4%). Histopathologic features were focal lymphocytic interface dermatitis with epidermal infiltration of CD8-positive lymphocytes. Patients with skin reactions had a significantly longer median overall survival compared to patients without any cutaneous events (34 versus 4 months, P < .001). LIMITATION: Monocentric study with a limited number of patients. CONCLUSION: Tebentafusp frequently induces cutaneous reactions. Pathogenesis is likely due to binding of tebentafusp to stimulated melanocytes in the skin, followed by infiltration and activation of lymphocytes. Development of treatment-induced skin reactions may be associated with survival benefits.

Characterisation of IL-1 family members in Sweet syndrome highlights the overexpression of IL-1ß and IL-1R3 as possible therapeutic targets.

Sweet syndrome (SS) as a prototypic neutrophilic dermatosis (NDs) shares certain clinical and histologic features with monogenic auto-inflammatory disorders in which interleukin (IL)-1 cytokine family members play an important role. This has led to the proposal that NDs are polygenic auto-inflammatory diseases and has fuelled research to further understand the role of IL-1 family members in the pathogenesis of NDs. The aim of this study was to characterise the expression of the IL-1 family members IL-1ß, IL-36γ, IL-33 and IL-1R3 (IL-1RaP) in SS. The expression profile of IL-1ß, IL-33, IL-36γ and their common co-receptor IL-1R3 was analysed by immunohistochemistry, in situ hybridisation and double immunofluorescence (IF) in healthy control skin (HC) and lesional skin samples of SS. Marked overexpression of IL-1ß in the dermis of SS (p < 0.001), and a non-significant increase in dermal (p = 0.087) and epidermal (p = 0.345) IL-36γ expression compared to HC was observed. Significantly increased IL-1R3 expression within the dermal infiltrate of SS skin samples (p = 0.02) was also observed, whereas no difference in IL-33 expression was found between SS and HC (p = 0.7139). In situ hybridisation revealed a good correlation between gene expression levels and the above protein expression levels. Double IF identifies neutrophils and macrophages as the predominant sources of IL-1ß. This study shows that IL-1ß produced by macrophages and neutrophils and IL-1R3 are significantly overexpressed in SS, thereby indicating a potential pathogenic role for this cytokine and receptor in SS.

Cutaneous lichenoid drug eruptions: A narrative review evaluating demographics, clinical features and culprit medications.

Cutaneous lichenoid drug eruptions (LDE) are adverse drug reactions (ADR) characterized by symmetric, erythematous, violaceous papules reminiscent but rarely fully characteristic of lichen planus (LP). We aimed to analyse the literature describing cases of LDE within the last 20 years to provide additional insight into culprit drugs, typical latency to onset of the eruption, the spectrum of clinical presentations, severity and management. A literature search was conducted in MEDLINE between January 2000 and 27 January 2021. The keywords 'lichenoid drug rash' and 'lichenoid drug eruption' were used. Cases were included if LDE diagnosis was made, and culprit drugs were identified. A total of 323 cases with LDE were identified from 163 published case reports and studies. The mean patient age was 58.5 years (1 month to 92 years), and 135 patients (41.8%) were female. Checkpoint inhibitors (CKI) were the most frequently reported culprit drugs (136 cases; 42.1%), followed by tyrosine kinase inhibitors (TKI) (39 cases; 12.0%) and anti-TNF-α-monoclonal antibodies (13 cases; 4.0%). The latency between initiation of the drug and manifestation was 15.7 weeks (range: 0.1-208 weeks). After discontinuing the culprit drug, the median time to resolution was 14.2 weeks (range: 0.71-416 weeks). One hundred thirty-six patients (42.1%) were treated with topical, and 54 patients (16.7%) with systemic glucocorticoids. Overall, we conclude that, albeit rare, LDE is challenging to diagnose ADR induced by mostly CKI, TKI, and biologics. Treatment modalities resemble that of lichen planus, and the culprit drugs had to be discontinued in only 26%, which is low compared with other types of adverse drug reactions. This is probably due to the low risk of aggravation (e.g. toxic epidermal necrolysis) if the drug is continued and the benefit/risk ratio favouring the drug, as is often the case in cancer therapy.

Mummified Cells are a Common Finding in Cutaneous Hodgkin Lymphoma and Can Be Used as a Diagnostic Clue.

Specific cutaneous involvement in Hodgkin lymphoma is rare. In cutaneous lesions, the diagnosis is usually based on the recognition of diagnostic Reed-Sternberg cells and its variants. In nodal Hodgkin lymphoma, so-called mummified cells (cells with condensed cytoplasm and pyknotic eosinophilic or basophilic nuclei) are often seen. They are sometimes conspicuous and easy to recognize, thus serving as a clue to the diagnosis. Our objective was to study cases of cutaneous Hodgkin lymphoma to identify the occurrence of mummified cells. We studied 12 patients (4 women and 8 men; age range 23-80 years). In 6 patients, cutaneous and extracutaneous disease was identified almost simultaneously; in 4 patients, lymph node disease preceded cutaneous involvement; and in the remaining 2 patients, the skin lesions were the presenting sign, whereas lymph node involvement occurred later. Histopathological, immunohistochemical, and molecular-genetic studies, including rearrangements for TCR, IgH genes, and PCR for EBV, were performed. Cutaneous biopsy specimens revealed either a multinodular or diffuse infiltrate, included small lymphocytes, eosinophils, plasma cells, and macrophages, but in all cases, diagnostic Reed-Sternberg cells and its variants were identified. Mummified cells were detected in 9 cases, either as occasional scattered mummified cells often requiring a search (6 cases) or being conspicuous, grouped and therefore easily identified (3 cases). Immunohistochemically, in all 7 cases studied, mummified cells were positive for both CD30 and CD15. It is concluded that mummified cells are encountered in a majority of cases of cutaneous Hodgkin lymphoma.

Dermoscopy and dermatopathology correlates of cutaneous neoplasms.

Dermoscopy is increasingly used by clinicians (dermatologists, family physicians, podiatrists, doctors of osteopathic medicine, etc) to inform clinical management decisions. Dermoscopic findings or images provided to pathologists offer important insight into the clinician's diagnostic and management thought process. However, with limited dermoscopic training in dermatopathology, dermoscopic descriptions and images provided in the requisition form provide little value to pathologists. Most dermoscopic structures have direct histopathologic correlates, and therefore dermoscopy can act as an excellent communication bridge between the clinician and the pathologist. In the first article in this continuing medical education series, we review dermoscopic features and their histopathologic correlates.

Usefulness of dermoscopy to improve the clinical and histopathologic diagnosis of skin cancers.

Multiple studies have shown that dermoscopy increases the sensitivity and specificity for the detection of skin cancers compared with examination by the naked eye. Dermoscopy can also lead to the detection of thinner and smaller cancers. In addition, dermoscopy leads to the more precise selection of lesions requiring excision. In essence, dermoscopy helps clinicians differentiate benign from malignant lesions through the presence or absence of specific dermoscopic structures. Therefore, because most dermoscopic structures have direct histopathologic correlates, dermoscopy can allow the prediction of certain histologic findings present in skin cancers, thus helping select management and treatment options for select types of skin cancers. Visualizing dermoscopic structures in the ex vivo specimens can also be beneficial. It can improve the histologic diagnostic accuracy by targeted step-sectioning in areas of concern, which can be marked by the clinician before sending the specimen to the pathologist, or by the pathologist on the excised specimen in the laboratory. In addition, ex vivo dermoscopy can also be used to select tumor areas with genetic importance because some dermoscopic structures have been related to mutations with theragnostic relevance. In the second article in this continuing medical education series, we review the impact of dermoscopy on the diagnostic accuracy of skin cancer, how dermoscopy can affect the histopathologic examination, and which dermoscopic features may be more relevant in terms of histologic and genetic prediction.

Syringocystadenoma Papilliferum of the Anogenital Area and Buttocks: A Report of 16 Cases, Including Human Papillomavirus Analysis and HRAS and BRAF V600 Mutation Studies.

Syringocystadenoma papilliferum (SCAP) is a benign tumor most commonly located on the head and neck area often associated with nevus sebaceus. In its usual location, the human papillomavirus (HPV) DNA and mutations in the RAS/mitogen-activated protein kinase signaling pathway have been detected in SCAP. We studied 16 cases of SCAP in the anogenital areas and buttock where this neoplasm is rare and attempted to find out whether SCAP in these sites have different histopathological and molecular biological features. It seems that there is no significant difference between the morphology of anogenital SCAP and SCAP in other locations. Several tumors in our cohort demonstrated features resembling those seen in warts, but HPV DNA was not found in these lesions. On the contrary, we identified DNA of HPV high-risk types in some tumors without HPV-related morphology. Our study confirms the role of HRAS and BRAF V600 mutations in the pathogenesis of SCAP, including SCAP in the anogenital areas and buttock.

TNFα and IL-17A are differentially expressed in psoriasis-like vs eczema-like drug reactions to TNFα antagonists.

BACKGROUND: Tumor necrosis factor α (TNFα) blocking drugs are in use for a wide range of autoimmune disorders. In up to 5% of patients, this class of drugs produces puzzling cutaneous side effects that are the subject of this investigation, namely psoriasiform and eczema-like skin inflammation. These side effects can occur after any time of treatment and regardless of the underlying disorders. The exact pathophysiology is as yet unknown. METHODS: A total of 33 patients (19 female, average age 52 years) who had a cutaneous reaction to infliximab, adalimumab or etanercept were included. The type of inflammatory reaction was determined, and the corresponding cytokine expression was evaluated by immunohistochemistry for TNFα, IL-1ß, IL-22, IL-6, IL-17A, IL33, IL-8 and IL-36α (semi-quantitative grading system from - to ++++). In addition, RNA expression levels of IL-17A and TNFα were confirmed by quantitative real-time PCR. RESULTS: IL-17A (P < .039) and TNFα (P < .008) were expressed at significantly higher levels in psoriasis or pustular-like reactions (PPR) compared to eczematous-like reactions (ELR). There was no significant difference in the expression of IL-1ß, IL-22, IL-6, IL-33, IL-8 and IL-36α between PPR and ELR. CONCLUSION: TNFα and IL-17A are both cytokines known to be involved in psoriasis but less so in non-psoriasiform dermatitis or eczema. Therefore, their overexpression in PPR is plausible and suggests that the pathogenesis of PPR mirrors at least in part those of psoriasis. Further investigations will define the exact role of these cytokines in rare cutaneous side effects of anti-TNFα therapy. Our results suggest that IL-17A inhibition could be a therapeutic option in patients with anti-TNF induced psoriasis.

Aggressive Rare T-cell Lymphomas with Manifestation in the Skin: A Monocentric Cross-sectional Case Study.

Rare T- or NK-cell lymphomas with cutaneous manifestation may display a highly aggressive clinical course and major diagnostic/therapeutic challenges. This report describes our experiences with different lymphomas of this rare category and the therapeutic options used. This retrospective, descriptive, monocentric, cross-sectional case study, identified 4 rare aggressive T-/NK-cell lymphomas with manifestation in the skin, which were diagnosed in a tertiary care centre over a period of 4 years. Two patients had an Epstein-Barr virus-associated extranodal NK/T-cell lymphoma and 2 patients had a primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma. Concomitant extracutaneous involvement was observed in 2 of all 4 patients. Two patients had fulminant disease progression and resistance to chemotherapy. Two patients underwent allogeneic haematopoietic stem cell transplantation, which resulted in one complete remission and one partial remission. This report emphasizes the importance of an early diagnostic work-up and a prompt aggressive therapeutic approach.

Sebaceous Neoplasms With Rippled, Labyrinthine/Sinusoidal, Petaloid, and Carcinoid-Like Patterns: A Study of 57 Cases Validating Their Occurrence as a Morphological Spectrum and Showing No Significant Association With Muir-Torre Syndrome or DNA Mismatch Repair Protein Deficiency.

Sebaceous neoplasms with an organoid pattern (rippled, labyrinthine/sinusoidal, carcinoid-like, and petaloid) are rare. Previous studies suggested that the above patterns likely represent variations along a morphological continuum. The objectives of this study were to (1) validate this proposition by studying a large number of cases, (2) determine whether there are specific associations with clinical features, (3) establish their frequency, and (4) determine whether they have any association with Muir-Torre syndrome. Fifty-seven sebaceous neoplasms (54 sebaceomas and 3 sebaceous carcinomas) with organoid growth patterns were studied. These occurred in 36 men and 18 women (sex unknown in 3), with ages at diagnosis ranging from 22 to 89 years (mean, 63 years). All patients presented with a solitary nodule (mean size, 11 mm) on the head and neck area. Of the 57 tumors, 24 manifested a single growth pattern, 23 had a combination of 2 patterns, and 10 a combination of 3 patterns, indicating that these patterns are part of a morphological continuum of changes. The carcinoid-like pattern was the most frequent in the "monopatterned" neoplasms (13 cases), whereas the labyrinthine/sinusoidal pattern comprised most of the "polypatterned" lesions, in which various combinations occurred. Immunohistochemically, mismatch repair protein deficiency was detected in 3 of the 22 cases studied, whereas 5 of the 33 patients with available follow-up had an internal malignancy/premalignancy. In conclusion, sebaceous neoplasms with organoid growth patterns are predominantly sebaceomas having a predilection for the scalp, occurring as solitary lesions in elderly patients (male to female ratio of 2:1). Such patterns are expected to be found in a quarter of sebaceomas. In most cases, more than one of the organoid patterns is present. These lesions do not appear to be associated with internal malignancy or mismatch repair deficiency in most cases. However, confirmation of the absence of any significant association with Muir-Torre syndrome syndrome will require genetic studies.

Cutaneous CD30-positive T-cell lymphoproliferative disorders-clinical and histopathologic features, differential diagnosis, and treatment.

Cutaneous CD30+ T-cell lymphoproliferative disorders (CD30+ LPD) are the second most common form of cutaneous T-cell lymphoma. CD30+ LPD include lymphomatoid papulosis, primary cutaneous anaplastic large-cell lymphoma, and borderline lesions. Despite expression of CD30 by the neoplastic cells as the hallmark of these disorders, they differ in their clinical presentation and histological features as well as the course, the prognosis, and consecutively in the treatment. Diagnosis of CD30+ LPD and distinction from the broad spectrum of differential diagnoses essentially depends on clinicopathologic correlation as well as the results of staging examinations. Although the histological findings indicate a high-grade lymphoma, CD30+ LPD in most cases have a favorable prognosis. Recent advances in targeted therapy have led to new therapeutic approaches to CD30+ LPDs. This review describes the clinicopathologic features of CD30+ LPDs, their differential diagnoses, the treatment, and the role of CD30 as a diagnostic marker and therapeutic target.

Clinical Disease Patterns in a Regional Swiss Cohort of 34 Pyoderma Gangrenosum Patients.

BACKGROUND/AIM: Pyoderma gangrenosum (PG) is a rare, neutrophilic dermatosis often associated with an underlying disease, and clinical data or larger studies are rare. METHODS: In this retrospective study, disease characteristics, clinical manifestations, and treatment response were evaluated in a Swiss cohort of PG patients. RESULTS: In participating centers, 34 cases (21 females) of PG were analyzed based on clinical and histological presentation between 2002 and 2012. The mean age at diagnosis was 61.2 years; 50% of the patients experienced only 1 episode of PG. In 13 cases (out of 20), recurrences occurred during PG therapy; 64.1% showed only 1 lesion simultaneously. The predominant localization was the lower limb (67%). The lesions were disseminated in 26.6%. At the time of diagnosis or recurrence, the mean diameter was 37.6 mm and the mean ulcer size was 10.3 cm2. C-reactive protein (CRP) was elevated in 73.2%; leukocytosis was present in 58.9% and neutrophilia in 50.9%. At least 1 associated comorbidity was present in 85% (the most prominent being cardiovascular disease). The most often used systemic treatments were steroids (68.3%), cyclosporine A (31.7%), dapsone (31.7%), and infliximab (13.3%), and the most often used topicals were tacrolimus 0.1% (48.3%) and corticosteroids (35%). PG healed completely at discharge in 50.8%. The average time to diagnosis was 8 months, and the mean duration to healing was 7.1 months. CONCLUSION: PG is a difficult-to-diagnose skin disease. Here, markers for inflammation such as CRP, leukocytosis, and neutrophilia were elevated in 50-73% of the PG patients.

The spectrum of skin biopsies and excisions in a pediatric skin center.

Little is known about the spectrum of pediatric skin disorders requiring biopsy/excision, their indication, impact on further management, and the accuracy of clinical diagnosis. We aimed to address these questions in the patient population seen at our Swiss University referral center for Pediatric Dermatology and Plastic Surgery. All skin biopsies/excisions performed in patients aged ≤ 16 years over a period of 2 years were retrospectively analyzed. A total of 506 samples were included. The majority of biopsies/excisions (n = 413, 82%) was performed for tumors, cysts, and hamartomas and 18% for other skin conditions. Malignant tumors were found in 12 samples (2%) from four patients. In 121 (24%) patients, the histopathology had an important impact on patient management. In 80 (16%) cases, the pathology did not match with the clinical diagnosis. In 382 (75%) cases, excision was the treatment of choice. Of these, the indication for surgery was based on patient's request in 181 (47%) cases. CONCLUSION: Surgical interventions for pediatric skin disorders are performed for diagnostic and therapeutic reasons. In this cohort, histopathology was essential for treatment in one quarter of cases. Skin tumors, cysts, and hamartomas often require excision during childhood, with families' request and esthetic considerations playing an important role. What is Known: • The spectrum of pediatric skin conditions has been studied in outpatient, inpatient, and emergency settings. • In contrast, no data exist on the spectrum of pediatric skin disorders undergoing biopsy/excision specifically. What is New: • We analyze biopsies/excisions in children, focusing on diagnosis, indication, and impact on patient management. • Surgical interventions for skin disorders in children are often performed for tumors and hamartomas with esthetic considerations playing a relevant role. If used for diagnostic purposes, they are often performed to confirm or rule out severe skin disease.

Anogenital Mammary-Like Glands: A Study of Their Normal Histology With Emphasis on Glandular Depth, Presence of Columnar Epithelial Cells, and Distribution of Elastic Fibers.

The normal histology of anogenital mammary-like glands (AGMLG) has been studied previously, but some aspects, including glandular depth, presence of columnar epithelium resembling columnar cell change/hyperplasia as defined in mammary pathology, and distribution of elastic fibers, have not been previously investigated. To address these issues, we studied 148 AGMLG identified in 133 paraffin blocks sampled from 64 vulvar wide excision or vulvectomy specimens (64 patients, various indications for surgery). The depth of AGMLG ranged from 0.64 to 3.9 mm. Epithelial columnar cell change was noted in 33.1% of all AGMLG, whereas columnar cell hyperplasia was detected in 10.1%. Occasionally, combinations of cuboidal epithelium and columnar cell change were seen within 1 histological section. Of 22 specimens stained for elastic fibers, in only 6 (27.3%) cases were elastic fibers found around glands. Periductal elastic fibers were demonstrated around 3 of the only 5 ducts, which were available for analysis in slides stained for elastic fibers. The depth of AGMLG should be taken into account when planning topical and surgical therapies for lesions derived or evolving from AGMLG. Alterations identical to columnar cell change may represent a normal variation of AGMLG.

Squared-Off Nuclei and "Appliqué" Pattern as a Histopathological Clue to Periocular Sebaceous Carcinoma: A Clinicopathological Study of 50 Neoplasms From 46 Patients.

The histopathological diagnosis of periocular sebaceous carcinoma can be difficult in poorly differentiated cases showing few mature sebocytes. The authors examined 50 periocular sebaceous carcinomas from 46 patients to determine the frequency of 2 features seen in this neoplasm, namely cells with squared-off nuclei and so-called "appliqué" pattern (peritumoral subnecrosis of peripherally located neoplastic cells). Neoplastic cells with squared-off nuclei were found in varying numbers in both the intraepithelial and dermal (invasive) components in all neoplasms, whereas the appliqué pattern was observed in a third of the cases. It is concluded that these features, taken together, may serve as a clue for the diagnosis of periocular sebaceous carcinoma.

Syringomatous Structures in Extramammary Paget Disease: A Potential Diagnostic Pitfall.

Primary extramammary Paget disease (EMPD) is a form of intraepithelial adenocarcinoma. Different morphological changes may accompany EMPD, including the presence of syringoma-like structures. The authors report 10 cases of EMPD, all of which manifested syringoma-like structures within the dermis both in areas involved by the carcinoma and beyond, including at the margins of the excisions. All patients were women, whose ages ranged from 49 to 93 years (median 75 years). The possible pathogenesis of the syringoma-like lesions is discussed. Awareness of these structures in vulvectomy specimens for EMPD is important to prevent misinterpretation of the syringoma-like lesions as an invasive component of the EMPD.

Syringocystadenocarcinoma Papilliferum In Situ-Like Changes in Extramammary Paget Disease: A Report of 11 Cases.

The authors report 11 cases of extramammary Paget disease (EMPD), all of which also demonstrated a combination of histological changes highly reminiscent of syringocystadenocarcinoma papilliferum in situ. In addition to the classical features of EMPD, characterized by the intraepidermal spread of individually dispersed neoplastic cells with ample cytoplasm, many of which contained mucin, there were areas of acanthosis with the substitution of spinous layer keratinocytes by neoplastic cells, whereas the native basal cell layer was intact. In addition to acanthosis (and sometimes papillomatosis), the dermal papillae showed a prominent infiltrate of plasma cells, completing the resemblance to syringocystadenocarcinoma papilliferum in situ; this similarity was further enhanced in 2 cases, which showed conspicuous gland formation. One additional case showed multifocal dermal proliferations compatible with eccrine syringofibroadenoma (syringofibroadenomatous hyperplasia). The changes described herein seem to be relatively rare in EMPD, and they can represent a diagnostic pitfall, as evidenced by 2 cases that were originally misinterpreted as syringocystadenocarcinoma papilliferum in situ. Clinically, these microscopic changes sometimes corresponded to nodular lesions, which were specifically noted to have a papillated erosive surface.

Neutrophilic Epitheliotropism is a Histopathological Clue to Neutrophilic Urticarial Dermatosis.

BACKGROUND: Neutrophilic urticarial dermatosis (NUD) comprises a particular autoinflammatory condition within the spectrum of aseptic neutrophilic dermatoses characterized by a distinct urticarial eruption clinically and a neutrophilic dermatosis histopathologically. OBJECTIVE: In this study, we reviewed skin biopsies of lesional skin of patients seen in our outpatient clinic for autoimmune dermatoses and in allergy department from 1982 to 2014 that fulfilled these criteria. METHODS: A total of 77 biopsies from 50 patients were analyzed histopathologically. Included were cases of Schnitzler syndrome, Still disease, systemic lupus erythematosus, Sjögren syndrome, cryopyrin-associated periodic syndrome, primary biliary cirrhosis, inflammatory bowel disease, and those that had signs of systemic inflammation not otherwise specified, that is, fever, arthritis, leukocytosis, and elevated erythrocyte sedimentation rate. A control cohort was defined as including a total of 70 biopsies from 50 patients comprising neutrophilic urticaria (pressure-induced and not pressure-induced), conventional urticaria, lupus erythematosus expressing neutrophils, and exanthematous drug reaction of macular type expressing neutrophils. RESULTS: Skin biopsies of NUD revealed a perivascular and interstitial neutrophilic infiltrate focally extending into the epithelia of epidermis, hair follicles, sebaceous and sweat glands, a feature which we termed neutrophilic epitheliotropism. This neutrophilic epitheliotropism proved to be of high sensitivity (83.1%) and lower specificity (74.3%). The histological findings could be substantiated by immunohistochemical markers for leukocytes (elastase and myeloperoxidase), in particular in cases where neutrophils showed uncharacteristic band-like nuclei. CONCLUSIONS: Neutrophilic epitheliotropism is a new sensitive and specific histopathological clue for NUD, a histopathological reaction pattern within the spectrum of neutrophilic dermatoses that needs to be differentiated from conventional urticaria.

Hidradenoma Papilliferum: A Clinicopathologic Study of 264 Tumors From 261 Patients, With Emphasis on Mammary-Type Alterations.

Hidradenoma papilliferum (HP), also known as papillary hidradenoma, is the most common benign lesion of the female anogenital area derived from anogenital mammary-like glands (AGMLG). HP can be viewed conceptually as the cutaneous counterpart of mammary intraductal papilloma. The authors have studied 264 cases of HP, detailing various changes in the tumor and adjacent AGMLG, with emphasis on mammary-type alterations. In many HP, the authors noticed changes typical for benign breast lesions, such as sclerosing adenosis-like changes, usual, and atypical ductal hyperplasia. Almost in a third of cases, remnants of AGMLG adjacent to the lesion were evident, manifesting columnar changes reminiscent of those seen in breast lesions. This study shows that the histopathological changes in HP run a broad spectrum comparable with that in the mammary counterpart and benign breast disease.