Histologic Hitchhikers: A Review of Common Exogenous Artifacts Encountered During Mohs Micrographic Surgery.

BACKGROUND: Exogenous artifacts can interfere with accurate histologic tissue evaluation on frozen sections during Mohs micrographic surgery (MMS). Mohs surgeons should be aware of these anomalies to avoid potential misdiagnoses. OBJECTIVE: To review exogenous artifacts encountered in frozen tissue pathology during MMS. METHODS: A literature search was conducted in PubMed to identify studies reporting on exogenous artifacts encountered during MMS and a list of previously described exogenous artifacts was compiled. A retrospective examination of frozen histology slides from recent Mohs cases at the authors' institution was performed to obtain illustrative examples of these artifacts, supplemented by formalin-fixed paraffin-embedded samples when frozen examples could not be found. RESULTS: Exogenous artifacts represent foreign bodies that have been externally introduced into the skin or artifacts resulting from other external factors. If frozen section evaluation is inaccurate, overdiagnosis can occur during MMS, resulting in unnecessary layers, larger margins, and more complex reconstructions. These exogenous tissue changes can mimic inflammatory processes and melanocytic or keratinocyte malignancies on histology. CONCLUSION: Exogenous artifacts are common findings during margin assessment in Mohs micrographic surgery. The resulting histological findings can be confusing but correlating them with the clinical and surgical history often reassures surgeons. Recognizing these artifacts facilitates accurate diagnosis and promotes optimal patient care.

Lichen amyloidosis of the scalp and forehead.

Lichen amyloidosis is a subtype of primary localized cutaneous amyloidosis (PLCA), which presents as discrete, firm, closely-set 1-3mm, dome-shapedbrown papules commonly involving the anterior aspect of shins and extensor surfaces of forearms. We present a case of an otherwise healthy man in his 30s with solitary facial involvement of lichen amyloidosis, which is very uncommon.

Tick Bite Alopecia: A Report and Review.

Tick bites can cause a number of local inflammatory reactions, which are often difficult to differentiate from those induced by other arthropod bites or stings. These include erythematous nodular or pustular lesions, erosive plaques, annular lesions of erythema chronicum migrans, and both scarring and nonscarring inflammatory alopecia. We report a case of nonscarring alopecia in a 21-year-old male who reported a recent history of tick bite to the scalp. The biopsy demonstrated a dense pseudolymphomatous inflammatory infiltrate with numerous eosinophils associated with hair follicle miniaturization and an elevated catagen-telogen count. Signs of external rubbing, including lichen simplex chronicus and the "hamburger sign", were also visualized and are indicative of the associated pruritus. To the authors' knowledge, this is the fifth report of nonscarring tick bite alopecia in the literature and the first in an adult patient. This text will review the classic clinical presentation, histologic findings, and proposed mechanism of tick bite alopecia.

Henoch-Schönlein Purpura with Posterior Reversible Encephalopathy Syndrome.

Henoch-Schönlein purpura is a common small-vessel vasculitis that presents in children as nonthrombocytopenic, nontender, and palpable purpura, arthritis/arthralgia, and abdominal pain. Central nervous system involvement is a reported, but likely, under-recognized complication. We present an 8-year-old boy with Henoch-Schönlein purpura and posterior reversible encephalopathy syndrome, after proposed mechanism and treatment considerations.

Lentigo Maligna Melanoma With Local and Distant Blue Nevus-like Metastases.

Melanoma or melanoma metastases can rarely mimic blue nevi clinically and/or histologically, presenting a diagnostic pitfall for both the clinician and the dermatopathologist. We report a case of an invasive lentigo maligna melanoma with subsequent development of multiple, cutaneous blue nevus-like localized metastases followed by a distant metastasis, heralding widespread systemic metastases.

Autologous graft-versus-host disease in a child with stage IV neuroblastoma.

Graft-versus-host disease (GVHD) is an underappreciated complication of autologous hematopoietic stem cell transplantation (AHSCT) that can affect the skin, gastrointestinal tract, and liver. The development of this rare condition is probably due to an impairment of immunologic tolerance that can occur spontaneously through T-cell dysregulation, possibly from intensive conditioning chemotherapy regimens, or intentionally through administration of cyclosporine in the hopes of promoting an antitumor response. We present the case of a 2-year-old boy with metastatic neuroblastoma who spontaneously developed autologous GVHD after AHSCT. Severe pruritus and an inability to taper his oral steroids without a disease flare marked his disease. Eventually partial relief was achieved with initiation of cyclosporine and a strict soak and smear protocol using topical triamcinolone 0.1% ointment.

A case of inflammatory nonscarring alopecia associated with the tyrosine kinase inhibitor nilotinib.

IMPORTANCE: Nilotinib, a recently approved multitargeted tyrosine kinase inhibitor targeting the BCR-Abl translocation involved in chronic myelogenous leukemia, reportedly produces alopecia according to the package insert, but clinical and histologic descriptions of the alopecia are lacking. OBSERVATIONS: A 33-year-old woman with chronic myelogenous leukemia developed widespread alopecia involving scalp and body hair within weeks after starting nilotinib therapy. Biopsies revealed perifollicular lymphocytic inflammation and evidence of follicular injury but normal hair density, consistent with a nonscarring alopecia. CONCLUSIONS AND RELEVANCE: Nilotinib therapy may induce perifollicular inflammation and widespread persistent alopecia. We present the first clinical and histologic description of this potential adverse effect. Further investigation into the underlying mechanism of this adverse effect may produce insights into the hair growth cycle as well as potential therapeutic targets.

Eczematous nevus sebaceus: a report of three cases.

Meyerson's phenomenon is a well-documented inflammatory reaction described in a variety of cutaneous lesions, including the original description in nevocellular nevi (1). Such an inflammatory reaction was subsequently described in melanocytic and a sundry of nonmelanocytic lesions alike, including vascular malformations (2-11). We present three cases of infants with nevus sebaceus on the scalp, which were obscured by an eczematous, eosinophilic reaction reminiscent of that first described by Meyerson. Two of the patients had concomitant atopic dermatitis, but one had no association. Recognition of this secondary feature is important in establishing the correct diagnosis.

Scleromyxedema presenting with neurologic symptoms: a case report and review of the literature.

Scleromyxedema is a rare variant of lichen myxedematosus. In addition to cutaneous manifestations, scleromyxedema often presents with systemic manifestations, including dysphagia, proximal muscle weakness, central nervous system disturbances, encephalopathy, and restrictive lung disease. It is almost always associated with paraproteinemia, usually IgG with gamma light chains. We review the literature on scleromyxedema associated with neurologic symptoms and present a case of a 49-year-old woman with encephalopathy attributable to scleromyxedema.

Histiocytic erythema multiforme.

Erythema multiforme is histologically characterized by liquefactive degeneration along the dermal-epidermal junction, necrotic keratinocytes and a lymphocytic infiltrate. We report a 10-year-old boy with recurrent erythema multiforme major of undetermined etiology with unusual histologic findings. A skin biopsy taken at day 2 of his eruption revealed histologic features otherwise characteristic of erythema multiforme, but mediated instead by a CD68-positive infiltrate, resembling cutaneous Kikuchi's disease. To the best of our knowledge this is the first reported case of 'histiocytic' erythema multiforme.