Cytophagic histiocytic panniculitis leading to a diagnosis of acute myeloid leukemia with monocytic differentiation: A case report and literature review.

Cytophagic histiocytic panniculitis (CHP) is associated with a number of systemic conditions and is characterized by the presence of benign phagocytic histiocytes ("bean bag cells"), including phagocytosed erythrocytes, leukocytes, and platelets. We describe a case of a 72-year-old female who presented with a papular eruption that clinically mimicked pityriasis lichenoides et varioliformis acuta (PLEVA). Given that her skin biopsy had multiple features concerning PLEVA, this diagnosis was classified as a superficial pityriasis lichenoides-like variant of CHP. The histopathologic presence of cytophagic histiocytosis prompted workup for a systemic malignancy, leading to a diagnosis of underlying acute monocytic leukemia of myeloid lineage.

Oral Nicotinamide for Actinic Keratosis Prevention in Kidney Transplant Recipients: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial.

BACKGROUND: Oral nicotinamide (NAM) has shown promise in preventing actinic keratoses (AKs) in trials based outside of the United States. We assessed the efficacy of oral NAM supplementation in kidney transplant recipients with a history of keratinocyte carcinoma. MATERIAL AND METHODS: Patients enrolled in a 2-week run-in phase, during which NAM 1000 mg was taken twice daily. After a washout period, patients who tolerated the run-in phase were randomized to NAM 500 mg twice daily or placebo. At baseline, 4, 8, and 12 months, dermatologists conducted full-body skin exams to document area-specific AKs. Routine lab work was collected to ensure the stability of renal allograft function. RESULTS: The dosage was reduced from 1000 to 500 mg due to gastrointestinal symptoms in the run-in phase. Patients were randomized to NAM (n = 10) or placebo (n = 11). At 12 months, mean AK count was 30.8 (95% CI -11.7-73.4) for NAM and 26.6 (95% CI 10.8-42.5) for placebo. The difference in percent AK count change at 12 months compared with baseline was 259.8% (95% CI -385.9 to 905.5) for NAM and 72.4% (95% CI -118.6 to 263.5) for placebo. The between-group difference in percent AK change was not significant (P = .38). There was no attrition in the placebo group and 40% attrition in the NAM arm. DISCUSSION: Nicotinamide did not decrease AK development among kidney transplant recipients. Limitations include drug tolerability, small sample size, and single-center trial nature.

Understanding melanoma in situ: Lentigo maligna surgical treatment terminology and guideline adherence, a targeted review.

BACKGROUND: Malignant melanoma in-situ, lentigo maligna (MMIS-LM) can be successfully treated with several different surgical techniques; however, the literature is inconsistent in defining them. OBJECTIVE: To comprehensively define and describe the national guideline recommended surgical techniques used to treat MMIS-LM to help clarify and standardize this terminology to ensure compliance with the guidelines. METHODS: A targeted literature review was performed from 1990 to 2022 focusing on articles that discussed the national guideline recommended surgical techniques of wide local excision, Mohs micrographic surgery (MMS), modified Mohs surgery, and staged excision/Slow-Mohs for MMIS-LM, as well as the related methods of tissue processing. National Comprehensive Cancer Network and American Academy of Dermatology guidelines were reviewed to identify how the techniques need to be employed to be compliant with guideline recommendations. RESULTS: We describe the various surgical and tissue processing techniques and discuss advantages and disadvantages of each. LIMITATIONS: This paper was styled as a narrative review defining and clarifying terminology and technique and does not investigate these topics more broadly. CONCLUSION: Understanding the methodology and terminology for these surgical procedures and tissue processing methods is critical so that both general dermatologists and surgeons can employ these techniques effectively for optimal patient care.

Host and primary tumor factors for the development of multiple cutaneous squamous cell carcinomas among a retrospective cohort in Rhode Island.

INTRODUCTION: Risk factors for a primary cutaneous squamous cell carcinoma (CSCC) are well-established; however, the host and primary tumor risk factors for subsequent CSCC have not been fully explored. METHODS: We performed a retrospective chart review of patients diagnosed with CSCC in an academic dermatology clinic in Rhode Island from 2016-2019. Logistic regression was used to evaluate the associations between host factors and multiple CSCC and between primary tumor characteristics and the risk of subsequent CSCC. Adjusted odds ratios (aORs) and 95% CIs were calculated. RESULTS: A total of 1312 patients with CSCC diagnoses were included. Host risk factors significantly associated with multiple CSCCs included: aged >80 years (aOR, 2.18; 95% CI, 1.46-3.31); history of: solid organ transplant (aOR, 2.41; 95% CI, 1.20-4.80); skin cancer (aOR, 1.96; 95% CI, 1.52-2.54); other cancer (aOR, 1.49; 95% CI, 1.11-2.00); family history of skin cancer (aOR, 1.36; 95% CI, 1.03-1.78); and actinic keratosis (aOR, 1.52; 95% CI, 1.18-1.95). Tumor location, diameter, histologic differentiation, and treatment were not significant predictors of subsequent CSCCs. LIMITATIONS: Study patients were predominantly White and from a single institution, limiting the generalizability of results. CONCLUSIONS: Certain host characteristics were associated with the development of subsequent CSCC, which may inform clinical guidelines for follow-up.

Segmental basaloid follicular hamartomas derive from a post-zygotic SMO p.L412F pathogenic variant and express hair follicle development-related proteins in a pattern that distinguish them from basal cell carcinomas.

Basaloid follicular hamartomas (BFH) are benign small basaloid skin tumors that can present as solitary or multiple lesions. Congenital BFH lesions arranged in a segmental distribution have been described, suggesting they derive from a somatic post-zygotic mutational event. Previously, BFH were described in Happle-Tinschert syndrome, which results from a post-zygotic SMO variant and is characterized by segmental BFH with variable involvement of the teeth, skeleton, and central nervous system. Here, we describe two patients with isolated segmental BFH and no systemic involvement. Paired whole exome sequencing of BFH and normal tissue revealed a pathogenic SMO c.1234 C>T, p.L412F variant restricted to BFH tissue. We characterized the proliferation index and expression of Hedgehog and Wnt/beta-catenin pathway related proteins in segmental BFH compared to sporadic basal cell carcinomas (BCCs) and found that segmental BFH had a lower proliferation index. Although segmental BFH expressed a similar level of Gli-1 compared to BCCs, levels of LEF-1 and SOX-9 expression in BFH were weaker for both and patchier for LEF-1. Our results show that a somatic SMO activating variant causes segmental BFH. Since these patients are prone to developing BCCs, differences in SOX9, LEF1, and Ki-67 expression can help distinguish between these two basaloid lesions.

"Kissing" basaloid follicular hamartomas of the eyelid.

Basaloid follicular hamartomas (BFHs) are rare, benign, cutaneous adnexal tumors characterized by branching cords and anastomosing strands of basaloid cells in a loose, fibrous stroma. BFHs exhibit variable clinical presentations although they are commonly observed as skin-colored papules and are diagnosed based on histopathological features. Common systemic diseases associated with BFH include alopecia, myasthenia gravis, and palmoplantar pitting. BFH of the eyelid is extremely rare with only five cases reported in the literature to date. Congenital "kissing" lesions have only previously been reported with nevi. Here, we present a novel case of congenital "kissing" BFH of the right upper and right lower eyelid, and histopathological examination revealed intradermal nodules of basaloid cells forming reticulated strands, pseudohorn cysts, mucinous stroma, and palisading with CD34 and Bcl-2 expression in the stromal fibroblasts and periphery, respectively.

Concominant bullous pemphigoid and cutaneous Crohn disease.

We report a case of new-onset bullous pemphigoid manifesting concurrently with cutaneous Crohn disease in a 58-year-old woman. Cutaneous Crohn disease is an extraintestinal manifestation of Crohn disease characterized by non-specific plaques or nodules. Bullous pemphigoid, a sub-epidermal autoimmune blistering disorder, has been observed in the setting of inflammatory bowel disease. The patient presented with recurrent bullae on the abdomen, thighs, and buttocks of 1 year's duration. She was not on any immunosuppressive therapies and had been treated with infliximab and azathioprine for her Crohn disease, which were discontinued 8 years before the blistering commenced. Punch biopsy of lesional skin showed a sub-epidermal blister with eosinophils. Sarcoidal and tuberculoid granulomas were present in the dermis. Direct immunofluorescence revealed linear 2+ IgG and 3+ C3 along the basement membrane. Indirect immunofluorescence was positive for BP180 and BP230 antibodies. These findings support the diagnosis of bullous pemphigoid with concomitant cutaneous Crohn disease. Both bullous pemphigoid and Crohn disease have been associated with an altered T-cell response. The similarities in the pathogenesis of the underlying inflammatory milieu suggest a possible etiopathogenic connection. This is believed to be the first report of cutaneous Crohn disease presenting simultaneously with bullous pemphigoid on histopathological examination.

Two Cases of Malignant Proliferating Trichilemmal Tumor (MPTT) and Review of Literature.

Malignant proliferating trichilemmal tumors (MPTTs, malignant proliferating pilar tumors) are theorized to originate from the outer root sheath of the hair follicle which resembles the isthmic portion of the hair follicle and epithelium of the lower hair follicle in catagen phase.1 They may develop de novo or arise from a pre- existing trichilemmal cyst or proliferating trichilemmal tumor. The tumors typically present with rapid growth on the scalps of women over the age of 50. In this review, we present two cases of MPTT, presenting on the scalp of a 69-year-old woman and the scalp of a 53-year-old woman. Both tumors were successfully treated with surgery and radiation. In addition to the classic histologic features, pilomatrical differentiation was also seen in case 1, a histologic feature that has rarely been described. In this paper, we review previously reported cases and summarize basic demographics, lesion size, location, treatment method, and patient outcome.

Two cases of congenital dermatomyofibroma.

We present two infants with histologically confirmed congenital dermatomyofibromas. Congenital cases are rare with only one prior case reporting presence since birth. Given the benign nature of the lesions and propensity of dermatomyofibromas to resolve without intervention in young male patients, no additional treatments were pursued.

Subungual Nail Erythrasma Presenting as Melanonychia: A Rare Finding.

Nail pathology may reflect a wide array of localized and systemic dermatological conditions. Certain nail findings such as melanonychia can create diagnostic challenges even to nail experts. We report a case of a 78-year-old man who presented with melanonychia of the great toe. Nail clipping showed focal melanin deposition, and dermoscopy demonstrated a region of localized erythema in the lunula concerning for possible melanocytic neoplasm. Subsequent nail biopsy showed numerous vertically oriented filamentous bacteria and coccobacilli within the nail plate consistent with a diagnosis of subungual nail erythrasma. Nail erythrasma is a rare entity. Additionally, this case highlights a new clinical presentation of nail erythrasma as melanonychia.

Paracicatricial melanocytes as a sign of melanoma.

Intradermal melanocytes in the setting of melanoma represent a diagnostic challenge to dermatopathologists as their presence may represent superficially invasive melanoma vs benign nevus cells or reactive dermal melanocytes. Previous dermatologic literature suggests that the absence of cytologic atypia in intradermal melanocytes and their presence in nonmelanocytic neoplasms lends to their characterization as reactive, benign, melanocytic proliferation. A 67-year-old female presented for evaluation of a 10-mm irregularly pigmented dark brown macule on the left cheek. Initial shave biopsy showed transected malignant melanoma measuring at least 0.6 mm in thickness. Multiple reexcision specimens demonstrated residual melanoma with banal appearing intradermal epithelioid melanocytes within and surrounding the scar. The melanocytes tracked into the skin graft, which had previously been free from involvement. Positron emission tomography-computed tomography (PET CT) and lymph node biopsies did not show evidence of metastatic melanoma. Ten months after her diagnosis and following five surgical excisions, the patient was diagnosed with metastatic melanoma to the brain and succumbed to intracranial hemorrhage. We present a case in which paracicatricial melanoma may simulate benign paracicatricial melanocytic hyperplasia. These findings have significant therapeutic and prognostic implications for the practicing dermatologist and dermatopathologist.