Dear Editor, Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare haematological malignancy arising from precursors of plasmacytoid dendritic cells. It constitutes less than one percent of acute leukaemias and frequently exhibits a distinct predilection for cutaneous involvement, especially in the initial stages of disease.1 The rarity, coupled with nonspecific skin findings, makes diagnosis particularly challenging and delays therapeutic intervention.2 We describe the case of a 58-year-old male, who presented with asymptomatic, gradually enlarging violaceous plaque and blackish nodules over the trunk and bilateral upper limbs for 3 months Figures 1 and 2. The lesions were firm, non-ulcerated, and non-tender, with no regional lymphadenopathy or systemic symptoms. No prior history of malignancy, autoimmune disease, or infection was reported. Systemic examination was unremarkable. Routine blood tests, including complete blood count and liver and renal function panels, were within normal limits.Figure 1: Multiple dark nodules over chestFigure 2: Erythematous to violaceous plaques and nodules over backA punch biopsy from one of the nodules revealed dense dermal infiltration by medium-sized blastic cells with scant cytoplasm, finely dispersed chromatin, and inconspicuous nucleoli Figure 3. The overlying epidermis was spared. On immunohistochemical staining, the tumour cells showed strong expression of CD4, CD56, CD123 and TCL-1, while being negative for lineage-specific markers such as CD3, CD20, CD30, CD34, and myeloperoxidase. These findings were consistent with a diagnosis of BPDCN.3Figure 3: Histopathological examination showing (a) 10 × dense dermal infiltration, (b) 40 × medium-sized blastic cells with scant cytoplasm, finely dispersed chromatin, and inconspicuous nucleoli (H and E)Subsequent staging investigations, including bone marrow aspiration and whole-body PET-CT, showed no evidence of systemic involvement. The patient was referred to the haemato-oncology department and was initiated on tagraxofusp, a CD123-targeted recombinant fusion protein. Partial clinical remission was achieved after two cycles; however, relapse occurred within 6 months. The disease progressed rapidly despite salvage chemotherapy, and the patient succumbed within 9 months of diagnosis. Although BPDCN is exceptionally rare, several multicentre and institutional series have documented its aggressive clinical course. Pagano et al.1 reported a median survival of less than one year in a multicentre cohort despite systemic therapy. Reimer et al.2 highlighted the historical use of CHOP-like chemotherapy and role of stem cell transplantation. Garnache-Ottou et al.3 and others emphasised the importance of early recognition and immunophenotyping. Pemmaraju et al.4 demonstrated that tagraxofusp led to initial responses in over 70 percent of treatment-naïve patients, though most experienced relapse within months. Sapienza et al.5 explored molecular targets including NF-κB and BCL-2 for future therapies. BPDCN typically affects elderly men and often presents deceptively. The violaceous skin lesions may mimic conditions such as cutaneous T-cell lymphoma, leprosy, lupus profundus, or sarcoidosis. In cases of persistent, atypical dermatoses unresponsive to standard therapy, a biopsy is essential. Diagnosis relies on immunophenotyping, with co-expression of CD4, CD56, and CD123 being diagnostic.4 While tagraxofusp has improved initial response rates, remissions are usually short-lived. Median survival remains under 18 months, and relapses are common.5 Newer therapies targeting BCL-2, NF-κB, and stem cell transplantation in selected patients are under investigation. This case highlights the dermatologist’s key role in recognising atypical presentations. Early biopsy and immunohistochemistry can lead to timely diagnosis and potentially improved outcomes. 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.
Kumari et al. (Fri,) studied this question.