Primary cutaneous large B-cell lymphoma of scalp: Case report of a rare variant.

Primary cutaneous large B-cell lymphoma (Bcl) is defined as a lymphoma composed of large cells constituting more than 80% of the infiltrate and absence of extracutaneous involvement after staging investigations. In the new World Health Organization/European Organization for Research and Treatment of Cancer classification, cutaneous Bcls with large cells are of three types - primary cutaneous large Bcl leg type (PCLBCLLT), primary cutaneous follicle center lymphoma diffuse type (PCFCLDT), and primary cutaneous large Bcls other (PCLBCLO). These three different types are distinct in terms of their clinicopathological features and survival. The PCLBCLO has intermediate features between those of PCLBCLLT and PCFCLDT. We present a case of PCLBCLO in a 57-year-old male who presented with a scalp swelling. Ultrasonography examination was suggestive of a sebaceous cyst. Computed tomography scan revealed the presence of an ill-defined hyperdense region in the soft tissue of the scalp region extending into the deeper layers of the scalp. Fine-needle aspiration cytology (FNAC) revealed the presence of atypical lymphoid cells. Diagnosis was confirmed by biopsy and immunohistochemistry. Patient received rituximab combined with doxorubicin, vincristine, cyclophosphamide, and prednisolone regimen with complete resolution of the lesion. We present this case for its rarity, the utility of FNAC in early diagnosis, and to discuss the differential diagnosis.