Case History {#sec1-1}
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Cutaneous pseudolymphomas are a group of benign reactive T- or B-cell lymphoproliferative processes of diverse etiology that simulate cutaneous lymphomas clinically and histologically. The diagnosis and classification of pseudolymphomas is a challenge for the clinical dermatologists and dermatopathologists. Though several causes have been illustrated in the literature, a definite cause fails to be elucidated. In spite of the fact that most cases microscopically resemble cutaneous lymphomas, they lead a clinically benign course. We report one such case of pseudolymphoma occurring in the groin of an elderly lady with a history of excision arthroplasty and cementing done at the same site decades ago.

Case Report {#sec1-2}
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A 67-year-old woman presented with an asymptomatic erythematous swelling in her left groin of 1 year duration. It was insidiously noticed a year back and had regrown over the past 4 months after a period of spontaneous and partial regression. There were neither complaints of pain, ulceration, bleeding or sinus formation from the lesion nor any preexisting dermatoses at the same site. There were no systemic complaints. Further enquiries revealed that the patient was hypertensive and had been on treatment with oral enalapril since many years. She sustained a fracture of the left hip 27 years ago which had healed poorly with arthritis of the joint, for which an excision arthroplasty was done with cementing to stabilize the joint. Cutaneous examination revealed a solitary, firm, erythematous, shiny, non-tender plaque measuring 8 × 4 cm in the left groin \[[Figure 1](#F1){ref-type="fig"}\]. There was no lymphadenopathy. Based on the history and clinical findings a differential diagnosis of pseudolymphoma was considered. Investigations such as complete blood picture, ESR, peripheral smear, urinalysis, liver and renal function tests, bone marrow aspiration and trephine biopsy, ultrasound of the abdomen, X-ray of chest, hip and pelvis were normal. A lesional biopsy showed hyperkeratotic epidermis with the absence of epidermotrophism and a dense diffuse infiltrate in the dermis extending to the subcutis composed of medium to large lymphoid cells \[Fiures [2](#F2){ref-type="fig"} and [3](#F3){ref-type="fig"}\]. The CD4 to CD8 ratio was normal and the immunohistochemical analysis showed diffuse staining for CD20 with a variable admixture of CD3 positive cells which was consistent with pseudolymphoma. CD30 and CD 23 were negative \[Figures [4](#F4){ref-type="fig"} and [5](#F5){ref-type="fig"}\].

![Pretreatment picture showing the large erythematous plaque in the groin](IJD-56-104-g001){#F1}

![Photomicrograph showing grenz zone with a dense lymphocytic infiltrate in the dermis (H & E 100×)](IJD-56-104-g002){#F2}

![Photomicrograph showing close up of the lymphocytic infiltrate witha perifollicular accentuation (H & E stain, 400×)](IJD-56-104-g003){#F3}

![Immunohistochemical staining with CD3 positive](IJD-56-104-g004){#F4}

![Immunohistochemical staining with CD20 positive](IJD-56-104-g005){#F5}

Our patient was started on hydroxychloroquin 400 mg daily based on the presumptive diagnosis of lymphocytoma cutis. Following 1 month of treatment the lesion showed clinically significant regression \[[Figure 6](#F6){ref-type="fig"}\]. The patient is currently under follow up and is doing well.

![Post treatment picture on treatment with Hydroxychloroquin](IJD-56-104-g006){#F6}

Discussion {#sec1-3}
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The prototypic lesion of pseudolymphoma is lymphocytoma cutis, also referred to as Spiegler Fendt sarcoid, lymphadenosis benigna cutis of Bafverstedt, cutaneous lymphoid hyperplasia, or cutaneous lymphoplasia.\[[@ref1]\] It is characterized by one or several nonscaling usually violaceous nodules or plaques most commonly on the head and neck, but can occur on the trunk and extremities. Though in most cases the cause is unknown, arthropod bites,\[[@ref2]\] trauma, tattoos,\[[@ref3]\] sun exposure, *Borrelia burgdorferi* infections,\[[@ref4]\] vaccinations,\[[@ref5]\] injected drugs for hyposensitization,\[[@ref6]\] acupuncture, gold pierced earrings,\[[@ref7]\] and post zoster scars\[[@ref8]\] have been reported in the literature to induce lymphocytoma cutis. The course is essentially benign and the lesions may persist for weeks, months, or years. They may show spontaneous regression however recurrences are common. As a rule there is no single reliable criterion to differentiate cutaneous pseudolymphomas from true lymphomas. Differentiation must always be made by a combination of clinicopathologic, immunohistochemical, and gene rearrangement studies and the long-term outcome. Whereas benign lesions are usually solitary, tend to regress spontaneously and rarely ulcerate, malignant lesions are multiple, larger, and often ulcerate. The traditional histologic diagnosis relies on the architectural pattern of the infiltrate and its cellular composition. The key histologic features that favor pseudolymphomas over true lymphomas include the presence of a polymorphous infiltrate which tends to be more superficially located (top heavy) with sparing of the epidermis and the narrow papillary dermis, whereas the infiltrate in lymphomas tends to be monomorphous, dense, and located deeply in the dermis and subcutaneous tissue (bottom heavy) as was evident in our case. Immunohistochemical methods may further help in distinguishing pseudolymphomas from true lymphomas where histologic differentiation may be difficult.\[[@ref9]\] Lymphomas and pseudolymphomas have been reported following silicone breast implants.\[[@ref10]\] But we believe this to be the first report of pseudolymphoma occurring 26 years after excision arthroplasty and cementing at the same site. Whether the surgery was contributory to the origin and pathogenesis of this lesion by the introduction of a foreign body in the form of cementing or purely coincidental is hard to prove. Nevertheless, our patient responded well to hydroxychloroquin. In cutaneous pseudolymphomas where a cause can be identified, removal of the causative agent generally leads to resolution; however in cases where the cause is unknown the course varies considerably. Topical and intralesional steroids, cryosurgery, interferon alfa, local irradiation and surgical excision, antimalarials, photochemotherapy, and cytotoxics have all been tried in its management.\[[@ref11]\]

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**Conflict of Interest:** Nil.
