Bullous pemphigoid (BP) most commonly presents as widespread, itchy, tense blisters in older patients. Localized bullous pemphigoid is a less common form of BP that can be more difficult to diagnose because of its similarity to more common conditions such as allergic contact dermatitis or bullous cellulitis. Prompt recognition of localized BP is important so that appropriate treatment can be started. We present a 57-year-old woman who presented with pruritic tense bullae overlying the surgical scar from a knee replacement 6 months prior on her anterior right knee. This case illustrates the potential for localized BP to be triggered by surgical procedures.

Exaggerated arthropod bite reactions causing hemorrhagic or necrotic bullous lesions can mimic other serious conditions such as cutaneous anthrax, brown recluse spider bite, and tularemia. A 55- year-old, healthy woman presented to the emergency department with a 3.5-centimeter painless, collapsed hemorrhagic bulla at the left costal margin. She was afebrile and had no systemic symptoms. Laboratory evaluation was unremarkable. She was prescribed silver sulfadiazine cream and mupirocin ointment. The area denuded two days later and the lesion completely healed. This case illustrates the broad differential to be considered when evaluating patients with hemorrhagic bullous lesions.

Eosinophilic dermatosis of hematologic malignancy (EDHM) is a dermatosis characterized by tissue eosinophilia that has been previously reported as insect bite-like reaction. It is a rare condition with a wide variety of clinical presentations ranging from papules, nodules, or blisters that simulate arthropod bites, to the formation of plaques of differing sizes. We report a case of eosinophilic dermatosis of hematologic malignancy in a patient with a hematoproliferative disorder.

Eosinophilic dermatosis of hematologic malignancy is a rare, paraneoplastic phenomenon that presents as a pruritic papular or vesicular eruption that is clinically and histopathologically similar to insect bites. We present a 56-year-old man with multiple relapses of diffuse large B cell lymphoma with a typical presentation of pruritic papules and vesicles on the extremities that correlate with a recent relapse of his lymphoma.

As one of the most abundant insect orders on earth, most Hemipteran insects are phytophagous, with the few hematophagous exceptions falling into two families: Cimicidae, such as bed bugs, and Reduviidae, such as kissing bugs. Many of these blood-feeding hemipteran insects are known to be realistic or potential disease vectors, presenting both physical and psychological risks for public health. Considerable researches into the interactions between hemipteran insects such as kissing bugs and bed bugs and their human hosts have revealed important information that deepens our understanding of their chemical ecology and olfactory physiology. Sensory mechanisms in the peripheral olfactory system of both insects have now been characterized, with a particular emphasis on their olfactory sensory neurons and odorant receptors. This review summarizes the findings of recent studies of both kissing bugs (including Rhodnius prolixus and Triatoma infestans) and bed bugs (Cimex lectularius), focusing on their chemical ecology and peripheral olfactory systems. Potential chemosensation-based applications for the management of these Hemipteran insect vectors are also discussed.

Eosinophilic annular erythema is an idiopathic acute eosinophilic dermatosis. It is a rare condition, with approximately 30 cases reported in the English literature. It features annular, figurate urticarial edematous plaques primarily affecting the trunk and proximal limbs. During evaluation of a patient, secondary causes of eosinophilic inflammation such as allergy-related conditions (eczema, drug, urticaria, contact dermatitis), parasitic infestations, and autoimmune dermatoses will need to be excluded. We present an unusual case of a 47-year-old patient who developed this condition.

Diffuse cutaneous mastocytosis with bullous formation is a rare childhood disease. We report a 5-month-old male who presented with a 3-week history of cutaneous bullae and pruritus. On examination, he had erythema of the cheeks bilaterally and diffuse slightly hyperpigmented, indurated skin on his trunk and abdomen. There were tense vesicles, bullae, and erosions linearly arranged on his trunk and extremities. Both the laboratory and imaging workup were normal. Subsequently, a punch biopsy of a vesicle on the abdomen was obtained and findings confirmed a diagnosis of diffuse cutaneous mastocytosis. An EpiPen(r) was prescribed due to the slightly increased anaphylaxis risk compared to other forms of mastocytosis. There are many purported triggers of diffuse cutaneous mastocytosis and there is currently no known cure which makes management of this disease challenging. This case highlights a rare condition for which official treatment guidelines do not exist. A prompt dermatologic diagnosis is necessary to ensure proper workup and regulation is in place.