CASE LETTER Lamotrigine-Induced Cutaneous Pseudolymphoma Kelly L. Reed, DO; Kelly B. Quinn, DO; Anthony J. Gust, MD PRACTICE POINTS • Cutaneous pseudolymphomas are a heterogenous group of benign T-cell, B-cell, or mixed-cell lympho- proliferative processes that resemble cutaneous lym- phomas clinically and/or histopathologically. copy • Cutaneous pseudolymphomas have many causative factors, including medications, infections, tattoo ink, vaccinations, and insect bites. • Lamotrigine is a potential inciting factor of cutaneous pseudolymphoma. not To the Editor: Do An 8-year-old girl presented with new lesions on the scalp that were mildly painful to palpation and had been increasing in size and number over the last 2 months. FIGURE 1. Lamotrigine-induced cutaneous pseudolymphoma Her medical history was remarkable for seizures, kera- presenting as 3 well-circumscribed, pink, slightly scaly nodules on tosis pilaris, and seborrheic dermatitis. The seizures had the vertex scalp. been well controlled on oxcarbazepine; however, she was switched to lamotrigine 6 months prior to presenta- tion under the care of her neurologist. The patient was of the scalp were negative. Two biopsies of lesions on the not taking other oral medications,CUTIS and she denied any scalp were performed, the first of which showed a non- trauma/insect bites to the affected area or systemic symp- specific lymphohistiocytic infiltrate. The second biopsy toms such as fever, fatigue, weight loss, nausea, swollen revealed a dense, nodular, atypical dermal lymphoid infil- lymph nodes, or night sweats. Physical examination trate composed primarily of round regular lymphocytes revealed 3 well-circumscribed, pink, slightly scaly, indu- intermixed with some larger, more irregular lymphocytes rated nodules on the frontal and vertex scalp (Figure 1). and few scattered mitoses (Figure 2). She reported pain on palpation of the lesions. Treatment Immunohistochemical studies revealed small B-cell with ketoconazole shampoo and high-potency topical lymphoma 2–positive lymphocytes with a 2:1 mix- corticosteroids was ineffective. ture of CD3+ T cells and CD20+CD79a+ B cells. The Over a period of 2 months after the initial presen- T cells expressed CD2, CD5, and CD43, and a sub- tation, the patient developed a total of 9 scalp lesions. set showed a loss of CD7. The CD4:CD8 ratio was Testing was performed 4 months after presentation of 10 to 1. No follicular dendritic networks were noted lesions. Bacterial and fungal cultures of the lesional skin with CD21 and CD23. Rare, scattered, medium-sized From the Department of Dermatology, Lehigh Valley Health Network, Allentown, Pennsylvania. Dr. Gust also is from Advanced Dermatology Associates, Ltd, Allentown. The authors report no conflict of interest. Correspondence: Kelly L. Reed, DO, 1259 S Cedar Crest Blvd, Allentown, PA 18103 ([email protected]). WWW.MDEDGE.COM/DERMATOLOGY VOL. 104 NO. 2 I AUGUST 2019 E1 Copyright Cutis 2019. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. LAMOTRIGINE-INDUCED CUTANEOUS PSEUDOLYMPHOMA A B FIGURE 2. A, A punch biopsy of a lesion on the right lateral scalp showed an atypical dermal lymphoid infiltrate (H&E, original magnification ×4). B, A punch biopsy of a lesion on the right lateral crown of the scalp showed a closer view of the atypical dermal lymphoid infiltrate with a nodular proliferation of round regular lymphocytes intermixed with larger irregular lymphocytes and scattered mitoses (H&E, original magnification ×20). CD30 cells were noted. Staining for CD10, B-cell lym- papules to even confluent erythroderma in certain cases.2 phoma 6, anaplastic lymphoma kinase, Epstein-Barr The high clinicalcopy variability further complicates diagno- virus–encoded RNA 1, IgD, and IgM were negative. The sis. Although our patient presented with 9 individual plasma cells had a κ/λ free light chain ratio of 2 to 1. nodular lesions, this finding alone is not sufficient to have Ki-67 was positive in 15% of lymphoid cells. Polymerase high suspicion for cutaneous pseudolymphoma without chain reaction analysis of T-cell receptor gene rearrange- including a much broader differential diagnosis. In our ment revealed a peak at 228 bp in a predominantly case,not the differential diagnosis also included cutane- polyclonal background. A thorough systemic workup ous lymphoma, arthropod bite reaction, lymphomatoid including complete blood cell count, immunoglobulin papulosis, tumid lupus, follicular mucinosis, lymphocytic assay, bone marrow transplant panel, comprehensiveDo infiltrate of Jessner, and leukemia cutis. metabolic panel, lactate dehydrogenase test, inflamma- The primary concern regarding diagnosis of cutaneous tory markers, and viral testing failed to reveal any evi- pseudolymphoma is the clinician’s ability to effectively dence of underlying malignancy. differentiate this entity from a true malignant lymphoma. After conferring with the patient’s neurologist, Immunostaining has some value by identification of lamotrigine was discontinued. Within a few weeks of ces- heterogeneous cell–type populations with a mixed T-cell sation, the scalp lesions resolved without recurrence at and B-cell infiltrate that is more characteristic of a benign 9-month follow-up. In addition to the lack of clinical, reactive process. Subsequent polymerase chain reaction histological, or immunohistochemical evidence of under- analysis can detect the presence or absence of mono- lying malignancy, the temporalCUTIS association of the devel- clonal T-cell receptor gene rearrangement or immuno- opment of lesions after starting lamotrigine and rapid globulin heavy chain rearrangement.3 If these monoclonal resolution upon its discontinuation suggested a diagnosis rearrangements are absent, a benign diagnosis is favored; of lamotrigine-induced cutaneous pseudolymphoma. however, these rearrangements also have been shown to Cutaneous pseudolymphoma is a term used to describe exist in a case of cutaneous pseudolymphoma that earned a heterogenous group of benign reactive T-cell, B-cell, or the final diagnosis when removal of the offending agent mixed-cell lymphoproliferative processes that resemble led to spontaneous lesion regression, similar to our case.4 cutaneous lymphomas clinically and/or histopathologi- Many different entities have been described as caus- cally.1 Historically, these types of proliferations have been ative factors for the development of cutaneous pseudo- classified under many alternative names that originally lymphoma. Of those that have been considered causative, served to describe only B-cell–type proliferations. With simple categories have emerged, including endogenous, advances in immunohistochemistry allowing for more exogenous, and iatrogenic causes. One potential endog- specific cell marker identification, cutaneous pseudolym- enous etiology of cutaneous pseudolymphoma is IgG4- phomas often are found to contain a mixture of T-cell related disease.5 A multitude of exogenous causes have and B-cell populations, which also led to identifying and been reported, including several cases of cutaneous pseu- describing T-cell–type pseudolymphomas.2 dolymphoma developing in a prior tattoo site.6 Viruses, The clinical appearance of cutaneous pseudolym- specifically molluscum contagiosum, also have been phoma is variable, ranging from discrete nodules or implicated as exogenous causes, and a report of cutaneous E2 I CUTIS® WWW.MDEDGE.COM/DERMATOLOGY Copyright Cutis 2019. No part of this publication may be reproduced, stored, or transmitted without the prior written permission of the Publisher. LAMOTRIGINE-INDUCED CUTANEOUS PSEUDOLYMPHOMA pseudolymphoma development at a prior site of her- watchful follow-up for these patients be carried out until pes zoster lesions has been described.7 Development of at least 5 years after the diagnosis of cutaneous pseudo- cutaneous pseudolymphoma in vaccination sites also has lymphoma is made to rule out the possibility of malignant been reported,8 as well as more obscure inciting events transformation, particularly in idiopathic cases.13 such as Leishmania donovani infection and medicinal 9 REFERENCES leech therapy. 1. Ploysangam T, Breneman D, Mutasim D. Cutaneous pseudolympho- A considerable number of reported cases of cutane- mas. J Am Acad Dermatol. 1998;38:877-898. ous pseudolymphoma have been attributed to drugs, 2. Bergman R. Pseudolymphoma and cutaneous lymphoma: facts and including monoclonal antibodies,10 herbal supplements,11 controversies. Clin Dermatol. 2010;28:568-574. and a multitude of other medications.1 As a class, anti- 3. Braddock S, Harrington D, Vose J. Generalized nodular cutaneous convulsants are considered more likely to cause lymph pseudolymphoma associated with phenytoin therapy. J Am Acad Dermatol. 1992;27:337-340. node pseudolymphomas than strictly cutaneous pseu- 4. Cogrel O, Beylot-Barry M, Vergier B, et al. Sodium valproate-induced 12 dolymphomas ; however, many drugs in this class of cutaneous pseudolymphoma followed by recurrence with carbamaze- medications have been described in the development of pine. Br J Dermatol. 2001;144:1235-1238. cutaneous pseudolymphoma.3 A review of the literature 5. Cheuk W, Lee K, Chong L, et al. IgG4-related sclerosing disease: a by Ploysangam et al1 revealed reports of the development potential new etiology of cutaneous pseudolymphoma. Am J Surg Pathol. 2009;33:1713-1719. of cutaneous pseudolymphomas after administration of 6. Marchesi A, Parodi P,