Hypercalcemia and Flower Cells on Peripheral Smear Revealing Human T-lymphotropic Virus Type 1 (HTLV-1)-Associated Adult T-cell Leukemia/Lymphoma

TL;DR

A rare case of adult T-cell leukemia/lymphoma is presented, marked by severe hypercalcemia and unique 'flower cells' in blood smears.

Contribution

This case highlights ATLL diagnosis without typical HTLV-1 risk factors, emphasizing the importance of recognizing flower cells and hypercalcemia.

Findings

Severe hypercalcemia was observed in a patient with ATLL.

Flower cells were identified on peripheral blood smear, suggesting acute-type ATLL.

The patient lacked known HTLV-1 risk factors, indicating possible underdiagnosis in non-endemic areas.

Abstract

Adult T-cell leukemia/lymphoma (ATLL) is a rare, aggressive peripheral T-cell malignancy caused by human T-lymphotropic virus type 1 (HTLV-1), most commonly affecting individuals from endemic regions. Diagnosis is challenging and often delayed due to low clinical suspicion and overlapping features with other hematologic and systemic disorders. A characteristic finding on peripheral blood smear is the presence of “flower cells,” atypical lymphocytes with deeply lobulated, petal-like, or cloverleaf nuclei and condensed chromatin, which is considered highly suggestive of acute-type disease. This case describes a 59-year-old female diagnosed with ATLL presenting with severe hypercalcemia and characteristic flower cells on peripheral smear, despite lacking recognized epidemiologic risk factors for HTLV-1 infection.

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