Leukemia Cutis of the Scalp Masquerading as 'Kerion' in a Child.

Abstract

Dear Editor, Dermatologic manifestations of leukemia can be both specific (leukemia cutis) and nonspecific (leukemids). Leukemia cutis (LC) is defined as neoplastic leukocyte (either lymphoid or myeloid lineage) infiltration into the epidermis, dermis, or subcutaneous tissues.[1] LC may have diverse presentation and may often be misdiagnosed clinically.[2] Histopathology and immunohistochemistry help to clinch the diagnosis of LC. Here, we describe a child who presented with a crusted lesion and patches of alopecia on the scalp mimicking kerion. A 8-year-old male child presented with crusted lesions over the vertex since 3 months. It started as a coin-shaped patch of alopecia, which was treated initially with topical indigenous plant extracts. This led to the formation of a blister, which progressed into a crusted plaque. At the same time, the child developed pain, intermittent fever, and swelling in the neck. A provisional diagnosis of kerion was made by family physician and the child was treated with a course of oral antibiotics and antifungals without any relief. Examination revealed yellowish crusted indurated plaque on the right side of the scalp measuring 8 × 6 cm [Figure 1]. There was another patch of alopecia measuring 3 × 4 cm on the left parietal region. Cervical lymph nodes (submandibular and occipital) were enlarged, tender, and hard in consistency. The child also had swelling of bilateral testicle. Hematological examination revealed anemia (Hb of 6.6g/dL), raised ESR (90 mm/hr), and low total lymphocyte count of 5730 per mL with 18% blast cells. Potassium hydroxide mount from skin scrapings and hair showed no fungal elements. Histopathological examination revealed ulcerated epidermis and dense infiltration with atypical lymphoid cells in the dermis, confirming the diagnosis of leukemia cutis [Figure 2]. Immunohistochemistry analysis of the lymph node biopsy showed that the atypical lymphoid cells were positive for CD45, PAX5, CD99, CD10, bcl6, bcl2, and c-myc and negative for CD 20, CD3, TdT, CD34, Cyclin D1, CD 138, CD 56, and CD117. Marrow aspiration studies revealed 67% blast cells and 20% lymphocytes. Flow cytometry of bone marrow aspirate reported positive B cell markers like CD10, CD19, and CD79a; and negative for CD20. Based on these findings, a diagnosis of Pre-B acute lymphocytic leukemia (ALL) was made.Figure 1: Crusted plaque with peripheral alopecia on the scalpFigure 2: (a) Diffuse infiltration by monotonous population of atypical lymphoid cells in the dermis with loss of skin adnexal structures. Acanthosis of epidermis could be appreciated (H and E, x100). (b) Monomorphic population of atypical lymphoid cells in the dermis showing blastoid morphology defined by high nuclear-cytoplasmic ratio, scant cytoplasm, and irregular clumped chromatin (H and E, x400)Leukemia is the most common malignancy in children; acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are the the most common forms of childhood leukemias.[3] LC has been found to be more common in AML than ALL. The most common cutaneous features of LC are papules and nodules followed by plaques; different morphological patterns may coexist in a given patient. It may not be possible to predict the type of underlying malignancy based on the morphology of skin lesions. Two main sites of predilection for LC in children are head and lower extremity.[3] In majority of patients, LC is the initial presenting manifestation of systemic disease. It can also be the manifestation of disease relapse. Rarely, it may precede by several months before the detection of leukemic cells in the peripheral blood (i.e., aleukemic leukemia).[23] Our patient presented initially with alopecia, which gradually progressed to form crusted plaque. Though irritant reaction following the use of plant extract would have led to the formation of a plaque, histopathology did not show significant spongiotic changes. ALL presenting as alopecia is an exceptional phenomenon. Potential pathophysiological mechanisms comprise malignant infiltration of the hair follicle and fibro-collagenous response to infiltration as well as cytokine release.[4] It is very important to perform a thorough general physical examination in a child presenting with alopecia; our case had scrotal swelling and cervical lymphadenopathy, which were hard in consistency. These features prompted us to suspect LC in this case. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.