Optimal hippocampal targeting in responsive neurostimulation for mesial temporal lobe epilepsy.

OBJECTIVE: The aim of this study was to identify features of responsive neurostimulation (RNS) lead configuration and contact placement associated with greater seizure reduction in mesial temporal lobe epilepsy (MTLE). METHODS: A single-center series of patients with MTLE treated with RNS were retrospectively analyzed to assess the relationship between anatomical targeting and seizure reduction. Targeting was determined according to both the preoperatively conceived lead configuration and the actual placement of RNS contacts. Three lead configurations were used: 1) single bilateral, with 1 depth lead in each hippocampus; 2) single unilateral, with 1 hippocampal depth lead and another implant outside the mesial temporal lobe; and 3) dual unilateral, with 2 leads in 1 hippocampus. Contact placement on postoperative imaging was measured according to the number of hippocampal contacts per targeted hippocampus (contact density) and per patient (contact count), distribution throughout the hippocampus, and proximity to the anteromedial hippocampus. RESULTS: Dual unilateral lead placement resulted in significantly higher hippocampal contact density compared with the single hippocampal approaches, but only showed a nonsignificant trend toward a higher rate of response. However, those patients with more than 4 contacts in a single hippocampus, achievable only with dual unilateral leads, had a significantly higher rate of response. The higher likelihood of response was poorly explained by more widespread hippocampal coverage, but well correlated with proximity to the anteromedial hippocampus. CONCLUSIONS: Dual unilateral hippocampal implantation increased RNS contact density in patients with unilateral MTLE, which contributed to improved outcomes, not by stimulating more of the hippocampus, but instead by being more likely to stimulate a latent subtarget in the anterior hippocampus. It remains to be explored whether a single electrode targeted selectively to this region would also result in improved outcomes.

Distinct Biomarkers of ANT Stimulation and Seizure Freedom in an Epilepsy Patient with Ambulatory Hippocampal Electrocorticography.

INTRODUCTION: Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) and responsive neurostimulation (RNS) of the hippocampus are the predominant approaches to brain stimulation for treating mesial temporal lobe epilepsy (MTLE). Both are similarly effective at reducing seizures in drug-resistant patients, but the underlying mechanisms are poorly understood. In rare cases where it is clinically indicated to use RNS and DBS simultaneously, ambulatory electrophysiology from RNS may provide the opportunity to measure the effects of ANT DBS in the putative seizure onset zone and identify biomarkers associated with clinical improvement. Here, one such patient became seizure free, allowing us to identify and compare the changes in hippocampal electrophysiology associated with ANT stimulation and seizure freedom. METHODS: Ambulatory electrocorticography and clinical history were retrospectively analyzed for a patient treated with RNS and DBS for MTLE. DBS artifacts were used to identify ANT stimulation periods on RNS recordings and measure peri-stimulus electrographic changes. Clinical history was used to determine the chronic electrographic changes associated with seizure freedom. RESULTS: ANT stimulation acutely suppressed hippocampal gamma (25-90Hz) power, with minimal theta (4-8Hz) suppression and without clear effects on seizure frequency. Eventually, the patient became seizure free alongside the emergence of chronic gamma increase and theta suppression, which started at the same time as clobazam was introduced. Both seizure freedom and the associated electrophysiology persisted after inadvertent DBS discontinuation, further implicating the clobazam relationship. Unexpectedly, RNS detections and long episodes increased, although they were not considered to be electrographic seizures, and the patient remained clinically seizure free. CONCLUSION: ANT stimulation and seizure freedom were associated with distinct, dissimilar spectral changes in RNS-derived electrophysiology. The time course of these changes supported a new medication as the most likely cause of clinical improvement. Broadly, this work showcases the use of RNS recordings to interpret the effects of multimodal therapy. Specifically, it lends additional credence to hippocampal theta suppression as a biomarker previously associated with seizure reduction in RNS patients.

Identifying the Sources of Racial Disparity in the Treatment of Parkinson's Disease With Deep Brain Stimulation.

BACKGROUND: Deep brain stimulation (DBS) is a highly efficacious treatment for appropriately selected patients with advanced, medically refractory Parkinson's disease (PD). It is severely underutilized in Black patients-constituting a major treatment gap. The source of this disparity is unknown, but its identification and correction are necessary to provide equitable care. OBJECTIVE: To identify sources of racial disparity in DBS for PD. METHODS: We predicted the demographics of potential DBS candidates by synthesizing published data on PD and race. We retrospectively examined the clinical course of a cohort including all patients with PD evaluated for DBS at our center from 2016 to 2020, testing whether the rate of DBS use and time from evaluation to surgery differed by race. We also tested whether the geographic distribution of patient catchment was biased relative to racial demographics. RESULTS: Far fewer Black patients were evaluated for DBS than would be expected, given regional demographics. There was no significant difference in the rate at which Black patients evaluated in our clinic were treated with DBS, compared with White patients. Fewer patients were recruited from portions of the surrounding area with larger Black populations. CONCLUSION: The known underuse of DBS in Black patients with PD was replicated in this sample from a center in a racially diverse metropolitan area, but was not attributable to the presurgical workup. Future work should examine the transition from medical management to surgical evaluation where drivers of disparity are potentially situated. Surgical practices should increase outreach to physicians managing PD in underserved areas.

The laterodorsal tegmentum and seizure regulation: Revisiting the evidence.

Electrical deep brain stimulation (DBS) is now a routine treatment option for patients suffering from medically refractory epilepsy. DBS of the anterior nucleus of the thalamus (ANT) has proven to be effective but, despite its success, few patients experience complete cessation of seizure activity. However, improving the therapy is challenging because the mechanism underlying its action remains largely unknown. One angle on improving the effectiveness of ANT stimulation is to better understand the various anatomic regions that send projections to and through this area. Here, the authors utilized a connectomic atlas of the mouse brain to better understand the regions projecting to the ANT and were particularly interested by the presence of robust cholinergic projections from the laterodorsal tegmentum (LDT). A subsequent review of the literature resulted in limited studies, which presented convincing evidence supporting this region's role in seizure control present in acute rodent models of epilepsy. It is thus the purpose of this paper to encourage further research into the role of the LDT on seizure mitigation, with mechanistic effects likely stemming from its cholinergic projections to the ANT. While previous studies have laid a firm foundation supporting the role of this region in modulation of seizure activity, modern scientific methodology has yet to be applied to further elucidate the mechanisms and potential benefits associated with LDT stimulation in the epileptic population.

Bioluminescence-Optogenetics: A Practical Guide.

Manipulation of neural activity in genetically predefined populations of neurons through genetic techniques is an essential tool in the field of neuroscience as well as a potential avenue in treating a vast assortment of neurological and psychiatric diseases. Here, we describe an emerging methodology of molecular neuromodulation termed bioluminescence-optogenetics (BL-OG) where BL is harnessed to activate bacterial light-driven channels and pumps expressed in neurons to control their activity. BL-OG is realized through opsin-luciferase fusion proteins called luminopsins (LMOs). In this chapter, we will provide a practical guide for applying BL-OG and LMOs in vitro using a cell line and primary cells in culture. In the following chapter, we will turn our focus towards BL-OG applications in ex vivo and in vivo rodent models of the nervous system.

Applications of Bioluminescence-Optogenetics in Rodent Models.

In the preceding chapter, we introduced bioluminescence-optogenetics (BL-OG) and luminopsin fusion proteins (LMOs), an emerging method of molecular neuromodulation. In addition to reviewing the fundamental principles of BL-OG, we provided a discussion of its application in vitro, including with cell lines and primary cells in culture in vitro. BL-OG is mediated by an easily diffusible molecule, luciferin, and when applied systemically in rodents, the substrate can spread throughout the body, including the brain, achieving powerful molecular neuromodulation with convenience even in awake and behaving animals. In this chapter, we provide a practical guide for BL-OG and LMO applications in rodent models of the nervous system, both ex vivo and in vivo.

Evidence supporting deep brain stimulation of the medial septum in the treatment of temporal lobe epilepsy.

Electrical brain stimulation has become an essential treatment option for more than one third of epilepsy patients who are resistant to pharmacological therapy and are not candidates for surgical resection. However, currently approved stimulation paradigms achieve only moderate success, on average providing approximately 75% reduction in seizure frequency and extended periods of seizure freedom in nearly 20% of patients. Outcomes from electrical stimulation may be improved through the identification of novel anatomical targets, particularly those with significant anatomical and functional connectivity to the epileptogenic zone. Multiple studies have investigated the medial septal nucleus (i.e., medial septum) as such a target for the treatment of mesial temporal lobe epilepsy. The medial septum is a small midline nucleus that provides a critical functional role in modulating the hippocampal theta rhythm, a 4-7-Hz electrophysiological oscillation mechanistically associated with memory and higher order cognition in both rodents and humans. Elevated theta oscillations are thought to represent a seizure-resistant network activity state, suggesting that electrical neuromodulation of the medial septum and restoration of theta-rhythmic physiology may not only reduce seizure frequency, but also restore cognitive comorbidities associated with mesial temporal lobe epilepsy. Here, we review the anatomical and physiological function of the septohippocampal network, evidence for seizure-resistant effects of the theta rhythm, and the results of stimulation experiments across both rodent and human studies, to argue that deep brain stimulation of the medial septum holds potential to provide an effective neuromodulation treatment for mesial temporal lobe epilepsy. We conclude by discussing the considerations necessary for further evaluating this treatment paradigm with a clinical trial.

Wheel running exercise protects against retinal degeneration in the I307N rhodopsin mouse model of inducible autosomal dominant retinitis pigmentosa.

Purpose: We previously reported that modest running exercise protects photoreceptors in mice undergoing light-induced retinal degeneration and in the rd10 mouse model of autosomal recessive retinitis pigmentosa (arRP). We hypothesized that exercise would protect against other types of retinal degeneration, specifically, in autosomal dominant inherited disease. We tested whether voluntary running wheel exercise is protective in a retinal degeneration mouse model of class B1 autosomal dominant RP (adRP). Methods: C57BL/6J mice heterozygous for the mutation in I307N rhodopsin (Rho) (also known as RHOTvrm4/+, or Tvrm4) are normal until exposed to brief but bright light, whereupon rod photoreceptor degeneration ensues. I307N Rho mice were given access to free spinning (active) or locked (inactive) running wheels. Five weeks later, half of each cohort was treated with 0.2% atropine eye drops and exposed to white LED light (6,000 lux) for 5 min, then returned to maintenance housing with wheels. At 1 week or 4 weeks after induction, retinal and visual function was assessed with electroretinogram (ERG) and optomotor response (OMR). In vivo retinal morphology was assessed with optical coherence tomography (OCT), and fundus blue autofluorescence assessed using a scanning laser ophthalmoscope. The mice were then euthanized, and the eyes fixed for paraffin sectioning or flatmounting. The paraffin sections were stained with hematoxylin and eosin (H&E) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) to assess retina morphology and apoptosis. Half of the flatmounts were stained for ZO-1 and α-catenin to assess RPE cell structure and stress. (We previously reported that translocation of α-catenin from cell membranes into the cytosol indicates RPE cell stress.) The remaining flatmounts were stained for ZO-1 and Iba-1 to assess the RPE cell size and shape, and inflammatory responses. Results: In vivo measures revealed that induction of the I307N Rho degeneration decreased retinal and visual function, decreased the thickness of the retina and photoreceptor layers, and increased the number of blue autofluorescence spots at the level of the photoreceptor-RPE interface. Post-mortem analyses showed that induction caused loss of photoreceptors in the central retinal region, and increased TUNEL labeling in the outer nuclear layer (ONL). The RPE was disrupted 1 week after induction, with changes in cell size and shape accompanied by increased α-catenin translocation and Iba-1 staining. These outcomes were partially but statistically significantly prevented in the exercised mice. The exercised mice that underwent induced I307N Rho degeneration exhibited retinal function and visual function measures that were statistically indistinguishable from that of the uninduced mice, and compared to the unexercised induced mice, had thicker retina and photoreceptor layers, and decreased numbers of subretinal autofluorescent spots. Post-mortem, the retina sections from the exercised mice that had undergone induced I307N Rho degeneration exhibited numbers of photoreceptors that were statistically indistinguishable from those of uninduced mice. Similarly, exercise largely precluded a degeneration-induced increase in TUNEL-positive cells in the ONL. Finally, the RPE of the exercised mice appeared normal, with a regular cell shape and size, and little to no alpha-catenin translocation or Iba-1 immunosignal. Conclusions: Voluntary wheel running partially protected against retinal degeneration and inflammation, and RPE disruption in a model of inducible adRP. This is the first report of exercise protection in an adult adRP animal model. It is also the first report of an RPE phenotype in the I307N Rho mouse. These findings add to a growing literature reporting that modest whole-body exercise is protective across a wide range of models of retinal damage and disease, and further highlights the potential for this accessible and inexpensive therapeutic intervention in the ophthalmic clinic.

Comparison of histologic findings in age-related macular degeneration with RPE flatmount images.

Purpose: To visualize and analyze ex vivo flatmounted human RPE morphology from patients with age-related macular degeneration (AMD), and to compare the morphology with histologic findings. To establish whether the sub-RPE structures identified en face in RPE flatmount preparations are drusen with histopathological registration in serial sections. To detect characteristic patterns found en face in RPE with the same structures in histological cross sections from eyes from cadavers of patients with AMD. Methods: Twenty-eight postmortem eyes from 14 patients (16 eyes with AMD and 12 age-matched control eyes) were oriented and microdissected yielding a RPE-choroid preparation. The tissues were flatmounted, stained with Alexa Fluor 635 Phalloidin (AF635-phalloidin) for f-actin and propidium iodide for DNA, and imaged using confocal microscopy. Portions of tissue from macular regions were processed for electron microscopic examination. After confocal imaging, the samples were remounted for histologic processing, embedded in paraffin, and serially sectioned perpendicular to the plane of the RPE-choroid sheet. Scaled two-dimensional (2D) maps of drusen locations found with the histological cross sections were constructed and correlated with the en face confocal microscopic images. Results: Twenty-eight postmortem eyes with a mean time of death to tissue preservation of 23.7 h (range 8.0­51 h) from 14 donors (seven women and seven men) with an average age of 78 years (range 60­93 years) were evaluated. Eight donors had AMD, and six served as controls. Scattered small, hard drusen were present in the periphery of the eyes with AMD and the healthy eyes. The macular region of the eyes with AMD contained small (<63 µm), medium (63.0­124 µm), and large ( ≥ 125 µm) drusen. The RPE was arranged in rosette-like structures overlying small drusen, attenuated overlying medium-sized drusen, and consisted of large multinucleated cells overlying large drusen. The RPE in the area of geographic atrophy was attenuated and depigmented. Conclusions: Confocal images of flatmounts from eyes with AMD showed RPE patterns overlying various types of drusen and geographic atrophy that correlated with histologic characteristics. We propose RPE repair mechanisms that may result in the patterns that we observed.

An integrated in vitro imaging platform for characterizing filarial parasite behavior within a multicellular microenvironment.

Lymphatic Filariasis, a Neglected Tropical Disease, is caused by thread-like parasitic worms, including B. malayi, which migrate to the human lymphatic system following transmission. The parasites reside in collecting lymphatic vessels and lymph nodes for years, often resulting in lymphedema, elephantiasis or hydrocele. The mechanisms driving worm migration and retention within the lymphatics are currently unknown. We have developed an integrated in vitro imaging platform capable of quantifying B. malayi migration and behavior in a multicellular microenvironment relevant to the initial site of worm injection by incorporating the worm in a Polydimethylsiloxane (PDMS) microchannel in the presence of human dermal lymphatic endothelial cells (LECs) and human dermal fibroblasts (HDFs). The platform utilizes a motorized controllable microscope with CO2 and temperature regulation to allow for worm tracking experiments with high resolution over large length and time scales. Using post-acquisition algorithms, we quantified four parameters: 1) speed, 2) thrashing intensity, 3) percentage of time spent in a given cell region and 4) persistence ratio. We demonstrated the utility of our system by quantifying these parameters for L3 B. malayi in the presence of LECs and HDFs. Speed and thrashing increased in the presence of both cell types and were altered within minutes upon exposure to the anthelmintic drug, tetramisole. The worms displayed no targeted migration towards either cell type for the time course of this study (3 hours). When cells were not present in the chamber, worm thrashing correlated directly with worm speed. However, this correlation was lost in the presence of cells. The described platform provides the ability to further study B. malayi migration and behavior.

Eruptive keratoacanthoma-type squamous cell carcinomas in patients taking sorafenib for the treatment of solid tumors.

BACKGROUND: Protein kinases (PKs) are indispensable for most cellular processes, and deregulation of PKs can lead to activation of oncogenic and anti-apoptotic pathways and immune dysregulation. OBJECTIVE: To report the development of keratoacanthoma (KA)-type squamous cell carcinomas (SCCs) in patients treated with the multikinase inhibitor sorafenib for the treatment of solid tumors, to present the possible mechanisms for induction of these SCCs, and to discuss the implications for discontinuation of therapy and possible cotherapies to decrease this side effect. PARTICIPANTS: Fifteen patients taking the multikinase inhibitor sorafenib for the treatment of solid tumors who developed multiple KA-type SCCs, which continued to develop while the patients were undergoing therapy but stopped with discontinuation of sorafenib. LIMITATIONS: This report is limited because it is a retrospective study that included only patients who developed multiple KA-type SCCs. CONCLUSIONS: Development of cutaneous SCCs appears to be a side effect limited to sorafenib, a multikinase inhibitor that inhibits not only multiple tyrosine kinases (TKs), but also the serine-threonine kinase Raf. The incidence of cutaneous SCCs does not appear greater with multikinase inhibitors that inhibit only TKs.

Dermatofibrosarcoma protuberans and giant cell fibroblastoma exhibit CD99 positivity.

According to most authors, dermatofibrosarcoma protuberans (DFSP) and giant cell fibroblastoma (GCF) represent the adult and juvenile forms, respectively, of the same disease entity, as evidenced by similar morphology, an identical chromosomal translocation, and CD34 positivity. It has been shown that DFSP and nuchal-type fibroma (NTF) (which is also CD34-positive) are related lesions, and that there might possibly be a continuum between the two. In addition, NTF exhibits CD99 positivity. It was therefore, hypothesized that both DFSP and GCF would show similar immunopositivity for CD99. Archives of pathology at several institutions were searched for DFSP and GCF tissue blocks. A total of 29 DFSP and 5 GCF were analyzed by immunohistochemistry for expression of CD99. Twenty-three of 29 DFSP (79%) and 2 of 5 GCP (40%) expressed CD99. Comparison of CD99 and CD34 showed that the non-tumoral periphery of DFSP was less probable to be CD99 positive, but this finding was not statistically significant.

Does imiquimod histologically rejuvenate ultraviolet radiation-damaged skin?

BACKGROUND: Imiquimod (IMI) 5% is believed by some to result in an improved cosmetic appearance of chronically ultraviolet radiation (UV)-damaged skin. OBJECTIVE: The objective was to determine what histologic and immunohistologic changes were present in actinically damaged skin after treatment with IMI. METHODS AND MATERIALS: Pre- and posttherapy biopsies of 12 patients with histories of actinic keratoses were evaluated with routine histology and immunohistochemical stains including p53, p63, proliferating cell nuclear antigen (PCNA), c-kit, and Factor XIIIa. RESULTS: After IMI therapy there was less compact hyperkeratosis, a more uniform rete ridge pattern with a more ordered proliferation of the epidermis, and a decrease in sun-damaged melanocytes. The papillary dermis showed a more uniform cellularity, and there was increased cellularity within the area of solar elastosis. After therapy, staining for p53, p63, and PCNA was decreased within the epidermis; staining for c-kit was decreased but more uniform in the basal cell; and Factor XIIIa expression was increased within the papillary dermis with a more ordered pattern of staining. CONCLUSION: These morphologic and immunohistochemical patterns may explain some of the improvement in overall skin appearance after IMI therapy and may be related to the spectrum of signaling pathways induced by the imidazoquinolines.

Nuclear expression of the antiapoptotic protein survivin in malignant melanoma.

BACKGROUND: Expression of the antiapoptotic protein survivin has been demonstrated in some melanocytic lesions and is believed to be required for melanoma cell viability. However, its diagnostic value in differentiating melanomas from nevi has not yet been examined. METHODS: Tissue microarray blocks were constructed with paraffin-fixed tissue of 19 nevi, 18 dysplastic nevi, 24 malignant melanomas, and 31 metastatic melanomas. Sections were then reacted with three antisurvivin antibodies (two monoclonal and one polyclonal) assessing labeling intensity (absent or weak, and moderate to strong) as well as the percentage of cells labeled (< 25%, > or = 25%). RESULTS: Of the antibodies evaluated, the polyclonal one was found to be the most sensitive. Nuclear immunoreactivity for survivin (i.e., > or = 25% of cells exhibiting and/or at least moderately intense staining) was seen in a subset of melanomas but not in nevi or dysplastic nevi (P < 0.05). CONCLUSIONS: Survivin is variably expressed in the cytoplasm in the entire spectrum of melanocytic lesions, with nuclear expression detectable only in melanomas. These data may underscore the importance of nuclear survivin in progression to melanoma and may prove useful in the differential diagnosis of melanoma versus nevus.

Distinctive clinical presentation of a NF-1 patient with loss of heterozygosity of PTCH in his epithelial tumors.

Although patients with neurofibromatosis (NF) have an increased incidence of tumors, there is only one study that suggests that NF1 patients may have an increased risk for epithelial malignancies. We present a patient with known NF1 who had developed multiple epithelial tumors since early in his life. All but one of these tumors were morphologically most consistent with trichoepitheliomas. Loss of heterozygosity (LOH) for Patched 1 gene (PTCH) was demonstrated within two of the trichoepitheloma-like tumors and one tumor diagnosed as basal cell carcinoma, and the patient was show to have a PTCH gene deletion. To our knowledge, a patient presenting with both NF1 and multiple trichoepitheliomas (MTE) has not previously been reported. The dysregulation in cellular proliferation and signaling induced by decreased NF1 along with the PTCH gene mutation may explain the pattern of immunohistochemical staining within these tumors, and the rare association of NF1 with epithelial neoplasms.

Unexplained hypereosinophilia and the need for cytogenetic and molecular genetic analyses.

BACKGROUND: Idiopathic hypereosinophilic syndrome (HES) is a diagnosis made after the exclusion of other causes of eosinophilia. However, differentiation of idiopathic HES from eosinophilic leukemia is sometimes difficult. In some cases, these diagnoses can be differentiated by cytogenetic or molecular findings, as illustrated in the patients described herein. OBSERVATIONS: We describe 3 patients with HES and associated pruritus; 1 patient also had recurrent lesions of eosinophilic cellulitis. All 3 patients were initially diagnosed as having idiopathic HES, but after evaluation and demonstration of molecular abnormalities, they were classified as having eosinophilic leukemia. CONCLUSIONS: Patients with a diagnosis of idiopathic HES should be evaluated for cytogenetic or molecular genetic abnormalities. These abnormalities can establish a diagnosis of chronic eosinophilic leukemia and may provide clues for emerging therapies.

Histologic features in primary cutaneous squamous cell carcinomas in immunocompromised patients focusing on organ transplant patients.

BACKGROUND: In organ transplant recipients (OTR) there is an increased incidence of cutaneous squamous cell carcinomas (CSCC), and they may be aggressive. OBJECTIVE: We wanted to determine whether any histologic features were characteristic or more common in CSCC of OTR. METHODS: A total of 518 immunocompetent individuals with 601 primary CSCC were examined. Seventy-nine OTR with 231 primary CSCC, 53 renal OTR, 25 heart/heart lung OTR, and 1 liver OTR were examined. RESULTS: In all patient populations, CSCC occurred dominantly in chronically sun-exposed skin. In OTR, however, a greater percentage occurred on the extremity, particularly the upper extremity, and they occurred at an earlier age. Features that were significantly more common in OTR were acantholytic changes, early dermal invasion, an infiltrative growth pattern with or without desmoplasia, and Bowen's disease with carcinoma. In OTR primary CSCC were also significantly deeper at time of diagnosis. CONCLUSIONS: Our findings confirmed the association of ultraviolet radiation exposure with development of CSCC in OTR. The increased depth of the primary CSCC in OTR is surprising because these patients are followed closely for skin cancer compared with immunocompetent patients. The other morphologic features that were significantly more common in OTR may theoretically reflect not only the type of iatrogenic immunosuppression in these patients, but also other procarcinogenic effects of their medications.

Delayed cutaneous reactions to heparin in antiphospholipid syndrome during pregnancy.

BACKGROUND: Clinical symptoms related to antiphospholipid antibodies often first occur during pregnancy with the diagnosis of antiphospholipid syndrome (APS). Unfractionated heparin (UFH) and low-dose aspirin are considered as first-line treatments for pregnant women with APS and recurrent fetal loss. However, in addition to an increased incidence of hemorrhagic side-effects and thrombocytopenia there are a number of drug eruptions with cutaneous components secondary to the use of UFH. One of these eruptions has been classified as a delayed type I.V. hypersensitivity reactions at the sites of UFH injections. The majority of these reactions occur in pregnant women. METHOD: We present three pregnant patients who developed delayed hypersensitivity reactions at the sites of UFH injections. Two patients had documented APS and the other patient had two previous spontaneous abortions. RESULTS: The histopathologic and immunohistochemical findings in the biopsy specimens from the sites of the delayed reactions were distinctive. The inflammatory infiltrate contained CD3+ and CD4+ lymphoid cells with plasma cells, and eosinophils. There was a marked increased in mast cells with increased stromal cells within the dermis and increased vascular proliferation. CONCLUSIONS: The distinctive histopathologic and immunohistochemical features seen in the delayed hypersensitivity reactions at the sites of UFH injections may be modulated by the immunomodulatory effects of UFH as well as the hormonal levels and cytokine patterns during pregnancy. Alternative therapies may not always be successful in resolving the reactions.