The role of proliferating cell nuclear antigen (PCNA) in differentiating idiopathic orbital inflammatory disease and lymphoid proliferations

Discovery of an unconventional lamprey lymphocyte lineage highlights divergent features in vertebrate adaptive immune system evolution

Lymphocyte receptors independently evolved in both jawed and jawless vertebrates with similar adaptive immune responses. However, the diversity of functional subtypes and molecular architecture in jawless vertebrate lymphocytes, comparable to jawed species, is not well defined. Here, we profile the gills, intestines, and blood of the lamprey, Lampetra morii, with single-cell RNA sequencing, using a full-length transcriptome as a reference. Our findings reveal higher tissue-specific heterogeneity among T-like cells in contrast to B-like cells. Notably, we identify a unique T-like cell subtype expressing a homolog of the nonlymphoid hematopoietic growth factor receptor, MPL-like (MPL-L). These MPL-L+ T-like cells exhibit features distinct from T cells of jawed vertebrates, particularly in their elevated expression of hematopoietic genes. We further discovered that MPL-L+ VLRA+ T-like cells are widely present in the typhlosole, gill, liver, kidney, and skin of lamprey and they proliferate in response to both a T cell mitogen and recombinant human thrombopoietin. These findings provide new insights into the adaptive immune response in jawless vertebrates, shedding new light on the evolution of adaptive immunity.

Nonsimultaneous bilateral nonrhegmatogenous retinal detachments presenting as a complication of panuveitis in the setting of idiopathic orbital inflammatory syndrome

BACKGROUND

Idiopathic orbital inflammatory syndrome (IOIS), also known as orbital pseudotumor, consists of a spectrum of idiopathic, nonneoplastic, noninfectious, space-occupying lesions, without identifiable local or systemic cause. This case demonstrates a unique presentation of IOIS associated with panuveitis and nonsimultaneous bilateral serous nonrhegmatogenous retinal detachments (NRRD).

METHODS

A 38-year-old man initially presented with a unilateral uveitis that progressed quite rapidly to a bilateral presentation. A diagnosis of IOIS was made after comprehensive blood work and imaging studies.

RESULTS

The patient had nonsimultaneous bilateral serous NRRD in the setting of panuveitis and IOIS. Retinal detachment is a rare complication of IOIS that has been reported only twice before. There are no prior reports in the literature of this unique triad of NRRD, panuveitis, and IOIS. The patient responded promptly to aggressive treatment with oral corticosteroids.

CONCLUSIONS

IOIS should be considered in the evaluation and management of patients with NRRD and panuveitis. Prompt diagnosis and treatment of IOIS with corticosteroids is important to yield good clinical response and significant visual recovery, as demonstrated by this case.

MRI patterns in orbital malignant lymphoma and atypical lymphocytic infiltrates

OBJECTIVE

To evaluate the potential of MRI in differentiating between malignant lymphomas and atypical lymphocytic infiltrates in the orbit.

MATERIALS AND METHODS

MRI, clinical and histopathological findings in 30 patients presenting with orbital lymphoproliferative diseases (malignant lymphoma and atypical lymphocytic infiltrates) were evaluated.

RESULTS

MRI detected 28 out of 30 (93%) orbital lymphoid tumors. Seven out of eight (87.5%) atypical lymphocytic infiltrates and 21/22 (95.4%) of malignant lymphomas were detected. One conjunctival malignant lymphoma and one conjunctival atypical lymphocytic infiltrate were missed. Only malignant lymphoma lesions were hyperintense compared to the extraocular muscles on precontrast and postcontrast T1-weighted images. The lacrimal duct was involved only with malignant lymphoma. Bilateral disease was more likely to be malignant lymphoma. Intraconal lesions were more likely to be associated with lesions elsewhere. No malignant lymphoma involved the extraconal fat. Only intraconal atypical lymphocytic infiltrates had indistinct margins.

CONCLUSION

In the orbit, MRI features alone may not allow clear-cut differentiation of malignant lymphomas from atypical lymphocytic infiltrates. However, certain imaging features increase the likelihood of distinguishing them. MRI may miss conjunctival disease. Both orbits should be imaged when orbital lymphoid disease is a probability. The presence of intraconal disease should prompt a search for lesions elsewhere. The use of a head coil instead of a superficial coil may be advantageous by eliminating coil shine effect and allowing evaluation of both orbits. Comparison of lesion signal to extraocular muscle signal appears to be a better alternative than cerebral gray matter or periorbital fat in differentiating malignant lymphoma from atypical lymphocytic infiltrates. Since imaging findings overlap, histopathological diagnosis is necessary in all cases.

Orbital imaging: Part 2. Intraorbital pathology

Several primary and secondary processes may affect the orbit. We present a review of intraorbital pathology utilising a compartmental approach guiding the differential diagnosis. Knowledge of the contents of each compartment facilitates the differential diagnosis. Globe pathology is not dealt with in this review.

Imaging of orbital lymphoproliferative disorders

Lymphomas and leukemias account for a large portion of orbital tumors. Orbital lymphoma accounts for 55% of malignant orbital tumors in adults. Idiopathic orbital inflammatory pseudotumors are pathologic entities that often challenge ophthalmologists and radiologists. This article describes the MR and CT features of orbital lymphoma, leukemia, and some other lymphoproliferative disorders.