Hidroacanthoma simplex is a rare benign intraepidermal adnexal tumor arising from the eccrine sweat duct and represents a distinct variant of eccrine poroma. Clinically, it often presents as a pigmented or verrucous plaque and may closely mimic benign or malignant cutaneous lesions, including seborrheic keratosis, Bowen disease, and pigmented basal cell carcinoma, leading to diagnostic challenges. We report the case of a 73-year-old woman who presented with a gradually enlarging hyperpigmented verrucous plaque over the right buttock, accompanied by a separate jet-black arcuate lesion over the breast. The clinical appearance raised suspicion of malignancy. Histopathological examination revealed marked acanthosis and hyperkeratosis with multiple well-circumscribed intraepidermal nests of uniform poroid cells demonstrating the characteristic Borst–Jadassohn phenomenon. The tumor cells were small and cuboidal with minimal atypia and showed focal duct-like luminal structures indicative of eccrine differentiation. These findings confirmed the diagnosis of hidroacanthoma simplex. The patient was advised complete surgical excision, and the postoperative course was uneventful with no evidence of recurrence on follow-up. This case highlights the diagnostic dilemma posed by pigmented variants of hidroacanthoma simplex and underscores the importance of histopathological evaluation in distinguishing it from malignant cutaneous neoplasms. Awareness of this entity and its characteristic features is essential for accurate diagnosis and appropriate management, especially in elderly patients presenting with atypical pigmented plaques. Early recognition helps prevent unnecessary aggressive treatment and ensures optimal patient outcomes.