Dermoscopy of Zosteriform Cutaneous Metastasis From Breast Adenocarcinoma

To the Editor: Breast cancer has the highest incidence of cutaneous metastasis when compared with other visceral malignancies.1 The clinical features vary enormously, which has consequently led to description of many morphological variants. The most common clinical type is nodular. Other reported but rare variants include generalized erythematous patches, sclerodermoid, erysipeloid, telangiectatic, alopecia neoplastica, “en cuirasse,” erythema-annulare-centrifugum-like, and bullous.2,3 Zosteriform cutaneous metastasis is one such rare presentation, frequently mimicking herpes zoster clinically.4 A 48-year-old Indian woman presented with skin lesions on her right arm, accompanied by profound itching and burning sensations for 3 months. She had been treated for herpes zoster with a course of antivirals by a primary care physician, with no improvement. The patient reported having undergone modified radical mastectomy for stage 2A invasive ductal adenocarcinoma in her right breast 3 years ago. After surgery, she completed 8 cycles of chemotherapy and has been taking oral tamoxifen since then. On examination, multiple pinhead to 4 mm sized, skin-colored, and erythematous, firm, shiny, mildly tender papules and a few nodules were present on the right axilla along the T2 dermatome (Fig. 1A). Similar papules in a grouped arrangement were also present on the right chest near axilla. Multiple enlarged axillary lymph nodes were present on the right side. Dermoscopic examination revealed discrete reddish-white lacunae separated by pale septae (Fig. 1B). Histopathological analysis showed dermis infiltrated with lymphovascular embolization by pleomorphic tumor cells having a high N:C ratio, scant cytoplasm, and enlarged hyperchromatic nuclei (Figs. 2A, B). Routine hematologic and biochemical examinations were normal. A diagnosis of zosteriform cutaneous metastasis secondary to breast carcinoma was made and the patient was referred to an oncologist for further treatment.FIGURE 1.: A, Clinical image showing skin-colored to erythematous papules on right axilla along T2 dermatome. Black arrow indicates an enlarged axillary lymph node. B, Dermoscopic image showing discrete reddish-white lacunae separated by pale septae (x20, polarized, dry, contact, DermLite DL5, San Juan Capistrano, CA, USA).FIGURE 2.: A, Histopathologic image: Epidermis showing mild-to-moderate acanthosis. Underlying dermis shows lymphovascular embolization by tumor cells (H&E, 40x). B, High-power view showing pleomorphic tumor cells having high N:C ratio, scant cytoplasm, and enlarged hyperchromatic nuclei (green arrow).Cutaneous metastasis can rarely manifest in zosteriform distribution, with only a handful of cases described worldwide, creating a diagnostic dilemma for general physicians.5 It has been reported in association with breast cancer, gastrointestinal and urothelial malignancies, lymphomas and squamous cell carcinomas.5 Several theories have been put forward to explain the zosteriform distribution including accidental surgical implantation of tumor cells, koebnerization at the site of previous zoster infection, and neural spread through the dorsal root ganglia, lymphatic or hematogenous spread.6 Our case had no history of herpes zoster infection, ruling out koebnerization. The presence of tumor cell emboli in the dermal lymphatics on histopathologic examination, together with the burning pain observed in the lesions, suggests that perineural lymphatic dissemination of tumor cells could be the underlying mechanism in our case. Dermoscopy features of cutaneous metastasis have been infrequently documented. Our findings of reddish-white lacunae separated by pale septae are probably related to the lymphovascular invasion of tumor cells, as explained in a previous case series.7 The prognosis of patients with cutaneous metastasis is poor with the median survival time of approximately 14 months after diagnosis.8 It is essential to monitor and actively investigate patients presenting with a dermatomal rash and a history of malignancy.