SkIndia Quiz 18: Multiple erythematous nodules in a 30-year-old woman.

A 31-year-old Hispanic woman presented with two months history of multiple, nontender, red-brown, and violaceous nodules of 0.5-1 cm in diameter [Figures 1a–c]. The lesions were disseminated to the face, earlobes, chest, back, and upper extremities. She denied any history of fever, weight loss, and night sweats. Two nontender 2 cm lymph nodes over the left cervical region were noted during physical examination. She was previously treated with systemic corticosteroids and oral antihistamines without improvement. Her complete blood count showed mild anemia and was otherwise healthy. The histopathological features from hematoxylin and eosin-stained tissue sections are shown in [Figures 2 and 3] and immunohistochemistry are shown in Figure 4.

Figure 1

Multiple infiltrated erythematous nodules on the patien's forehead (a), right cheek (b) and right earlobe with an infiltrated aspect (c)

Figure 2

Skin biopsy stained with H and E, ×10. Periadnexal and deep dermal B-cell type lymphoblastic infiltrate

Figure 3

Skin biopsy stained with H and E, ×40. Monomorphic infiltrate of large lymphoid cells with pleomorphic nuclei and thin basophilic cytoplasm

Figure 4

Skin biopsy diffuse staining of cells with terminal deoxynucleotidyl transferase, ×10

ANSWER

Acute lymphoblastic leukemia with cutaneous infiltration.

DISCUSSION

Leukemia cutis (LC) results from the cutaneous infiltration of neoplastic leukocytes and occurs in 10–15% of patients[1] with acute myeloid leukemia in contrast to <1% of patients with lymphoblastic leukemia,[2] and is more frequent in children.[3] Lesions present as firm violaceous, red-brown, or hemorrhagic papules, nodules and plaques, most commonly affecting the legs. Differential diagnoses include fixed drug eruption, drug reactions, sarcoidosis, lymphomas, metastases, and leprosy. Diagnosis is histopathological, based on the characteristics of skin infiltration and type of tumor cells,[4] but immunophenotyping through a bone marrow aspirate is imperative.[5] T-cell, B-cell and myeloid markers can also be assessed in formalin-fixed skin biopsies. The most common markers expressed in B-cell precursor lesions are Pax-5/BSAP (present in all stages of B-cell development) and terminal deoxynucleotidyl transferase; combined stainings are made to identify B-cell lymphoblastic leukemia/lymphoma.[2] Because LC is a cutaneous manifestation of an underlying systemic disease, and is usually associated with a poor prognosis, aggressive chemotherapy should be started once the diagnosis is made.