Multiple erythematous nodules in a 30-year-old woman.

Sir,

We write this letter in response to the article titled “Multiple erythematous nodules in a 30-year-old woman,” published in your esteemed journal in the May–June 2015 issue in the quiz section.[1]

According to the authors, the female patient presented with a two month history of red-brown and violaceous nodules over face, earlobes, chest, back, and upper extremities. Apart from two enlarged lymph nodes over the left cervical region, there were no systemic findings. Her complete blood count showed mild anemia and was otherwise healthy. Skin biopsy stained with hematoxylin and eosin (H and E) revealed periadnexal and deep dermal B-cell-type lymphoblastic infiltrate and there was diffuse staining of cells with terminal deoxynucleotidyl transferase (TdT). Subsequently, the authors diagnosed her as acute lymphoblastic leukemia (ALL) with cutaneous infiltration.

We would like to point out in this regard that the diagnosis of ALL should not be made in the absence of a peripheral smear and a bone marrow aspiration and biopsy. Although white blood cell count may be normal in these patients, National Comprehensive Cancer Network (NCCN) guidelines note that diagnosis of ALL generally requires the following:[2]

Demonstration of ≥20% bone marrow lymphoblasts

Morphologic assessment of Wright/Giemsa–stained bone marrow aspirate smears

H and E–stained bone marrow core biopsy and clot sections

Comprehensive flow cytometric immunophenotyping.

Thus, bone marrow aspiration and biopsy are the definitive diagnostic tests to confirm the diagnosis of leukemia, a fact acknowledged by the authors in their discussion.

TdT is a DNA polymerase enzyme, which is expressed in undifferentiated clones of migrating lymphoid cells.[3] Although most cases of ALL are positive for TdT, the latter is not specific for ALL. High levels of TdT are also encountered in chronic myelogenous leukemia (CML), a number of acute undifferentiated leukemia (AUL) and lymphoblastic lymphomas.[3]

Out of the lymphoblastic lymphomas, precursor B-lymphoblastic lymphoma (P-LBL) usually involves skin, soft tissue, bone, and lymph nodes.[4] Therefore it may also be considered as a differential in this case.

In the scenario of peripheral blood smear and bone marrow aspiration being noncontributory, the diagnosis then considered in this case would be “Aleukemic leukemia cutis,” a condition where skin involvement by leukemic cells precedes peripheral blood or bone marrow involvement.[5]

Because an accurate diagnosis of subtype of leukemia/lymphoma will lead to appropriate management of such a case, we wish to reiterate the importance of a peripheral blood smear and a bone marrow aspiration and biopsy to make a diagnosis of lymphoma/leukemia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.