# Malignant skin adnexal tumor of the finger with late metastases

## TL;DR

A rare skin tumor in a finger led to late metastases in the brain and lungs, highlighting the difficulty in diagnosing and predicting its spread.

## Contribution

Expands the known radiologic features of malignant cutaneous adnexal tumors, including a rare multilobulated cystic brain metastasis.

## Key findings

- Malignant spiradenocylindroma initially misdiagnosed as a hematoma or foreign-body reaction.
- Metastases appeared 8 years after amputation in the brain and lungs, leading to a fatal outcome.
- MRI and PET/CT revealed infiltrative mass, bone destruction, and metabolically active metastases.

## Abstract

Malignant cutaneous adnexal tumors (MCATs) are rare neoplasms with unpredictable metastatic behavior and limited radiologic characterization. We report a case of malignant spiradenocylindroma initially evaluated with ultrasound, which demonstrated a pear-shaped heterogeneous subcutaneous structure with slight peripheral hyperemia and a small fluid-filled component in the distal phalanx of the left third finger, interpreted as a possible post-traumatic hematoma or foreign-body reaction consistent with the clinical history. Three years later, magnetic resonance imaging (MRI) revealed an infiltrative, contrast-enhancing mass with adjacent bone destruction, confirming a malignant process. After amputation, the patient remained disease-free for 8 years before developing neurological symptoms. Brain MRI showed an unusual multilobulated cystic metastasis, and positron emission tomography combined with computed tomography (PET/CT) demonstrated metabolically active pulmonary metastases. The patient ultimately experienced a fatal outcome. This case highlights the diagnostic challenges in early presentation and underscores the potential for delayed distant metastases in MCATs while expanding the radiologic spectrum of intracranial involvement to include rare multilobulated cystic presentations.