Zosteriform cutaneous metastases from an occult primary malignancy of lung identified by whole-body FDG PETCT imaging.

Cutaneous metastasis may be the first evidence of internal malignancy or a sign of recurrence of malignancy and is considered a grave prognostic sign. There are various morphological variants of cutaneous metastases, with the most common being solitary to multiple erythematous infiltrating papules and nodules and the rarer variants being carcinoma erysipeloides, carcinoma en cuirasse, carcinoma telangiectaticum, alopecia neoplastica, metastasis to the inframammary crease, and zosteriform pattern. FDG PETCT is an established imaging modality in the identification of an unknown primary malignancy and also has an important role in the therapeutic decision-making.

INTRODUCTION

Zosteriform metastases are cutaneous metastases, which occur in a dermatomal distribution. It may be the first evidence of an internal malignancy or a sign of recurrence of malignancy and is considered a grave prognostic sign. Lungs, breast, nasopharynx and pancreatic malignancies can present with cutaneous metastases. These cutaneous deposits are usually nodular but other forms of cutaneous distribution reported are erysipeloid, telangiectatic, alopecia neoplastica, generalized erythematous patches, eberneum, 'en cuirase', erythema annulare centrifugum-like, and bullous zosteriform metastases. Zosteriform pattern is a very rare type of cutaneous metastases and we present one such case of occult lung malignancy with initial manifestation in the form of zosteriform cutaneous metastases.

CASE REPORT

A 75-year-old male presented with a 3 months history of painless erythematous, papulonodular skin lesions involving anterior chest wall with some pin-head vesicles [Figure 1]. He presented to a local physician and was treated for herpes zoster in view of dermatomal distribution of the lesions. The lesions however progressed extending to the neck on both sides and he started experiencing pain over the right angle of mandible extending up to parotid region. He developed hoarseness of voice and difficulty in swallowing. A week later, he developed multiple areas of fungating growth over the chest with oozing of blood from the lesions. He was referred to oncology. On local examination, positive findings include bilateral cervical lymphadenopathy, left parotid enlargement, and fungating growth over the upper infraclavicular left chest wall and left side of neck. On palpation, there was woody hard induration over the right and left sides of neck. Laryngoscopy revealed absence of bilateral vocal cord abduction suggesting bilateral recurrent laryngeal nerve palsy. Hemogram was normal. C-reactive protein was raised (93 mg/ml, normal is <1). Tumor markers were elevated (carbohydrate antigen [CA] 19-9 was 1680.5 U/ml and carcinoembryonic antigen [CEA] was 2936.1 ng/ml, normal range is 0–37.0 U/ml for CA 19-9 and 0–5 ng/ml for CEA, respectively).

Figure 1

Zosteriform cutaneous metastases – Patient depicting skin rashes (painless erythematous, papulonodular skin lesions) over anterior chest and neck with matching much more extensive fluorodeoxyglucose avid cutaneous lesions over chest, bilateral neck, and right shoulder in the fluorodeoxyglucose positron emission tomography/computed tomography coronal image

A clinical diagnosis of zosteriform cutaneous metastases was made by the oncologist and biopsy was performed from the representative lesions which showed cells arranged in lobules, glandular, and trabecular pattern starting from just beneath the epidermis and infiltrating between the appendages, arrector pili, and into the deeper tissues. Features were suggestive of an adenocarcinoma with focal pagetoid spread which may represent metastatic deposits or primary adnexal tumor in a male. Immunohistochemistry was cytokeratin 7-positive, cytokeratin 20-negative, CEA-positive, and thyroid transcription factor 1-negative, indicating one of the followings: Primary pancreaticobiliary, lung, stomach, or a salivary gland malignancy.

The patient was referred for a whole-body 18Fluorine-labeled fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) to look for unknown site of primary malignancy. Seven millicuries of FDG were injected intravenously in euglycemic status and whole-body imaging with contrast-enhanced CT was acquired an hour later with 8-slice GE discovery PET/CT system. PET/CT images revealed an FDG avid spiculated soft tissue lesion in apical segment of right upper lobe lung (maximum standardized uptake value [SUVmax 4.8]) with multiple FDG avid mediastinal lymph nodes [Figures 2 and 3]. There were multiple metabolically active bilateral cervical and axillary lymph nodal deposits along with left parotid gland metastatic deposits. The cutaneous lesions correspond to FDG avid enhancing nodular soft tissue deposits in right shoulder, bilateral neck, and anterior chest wall (SUVmax 10.2). He was started on palliative chemotherapy with paclitaxel and carboplatin (Cycle-1). He succumbed 10 days later.

Figure 2

Fluorodeoxyglucose avid spiculated soft tissue lesion in apical segment of right upper lobe lung (maximum standardized uptake value 4.8) seen in the transaxial positron emission tomography/computed tomography images (contrast-enhanced computed tomography was performed)

Figure 3

Transaxial positron emission tomography/computed tomography images reveal (a) hypodense fluorodeoxyglucose avid left parotid gland metastases, (b) fluorodeoxyglucose avid multiple mediastinal, axillary nodal deposits and cutaneous metastatic lesions over anterior chest wall

DISCUSSION

Metastatic skin cancer is a relatively rare complication of internal malignancies. It has been reported to occur in 0.7–9% of patients with internal malignancies.[1] Zosteriform pattern is a very rare type of cutaneous metastases with only a few reported cases.[2] The mechanism of zosteriform distribution often remains unknown; however, proposed theories include lymphatic spread, koebnerization at the site of previous zoster infection, surgical implantation of tumor cells, and neural spread via the dorsal ganglia.[3] The percentage of patients with lung cancer that develops cutaneous metastases ranges from 1% to 12%.[4] Literature search shows that lungs, pancreas, and oropharynx are the most frequently affected sites in suspected cases of unknown primary. FDG PET/CT has proved to be quite sensitive for the detection and evaluation of pulmonary nodules. Its role in diagnosis, staging, and restaging of nonsmall cell lung cancer, small cell lung CA, and pleural disease has also been well established.[5] Uptake of FDG (SUV) serves as a semi-quantitative measure in identifying a lesion to be benign or malignant. The most widely used cutoff for any lesion to be called malignant is an SUV of above 2.5. With application of qualitative criteria, FDG PET is approximately 95% sensitive and 80% specific for malignancy and with quantitative criteria, sensitivity has decreased to 81% and specificity to 87%.[6789]

Cutaneous metastases and their primaries in the lung are usually incurable and suggest an unfortunate prognosis. Poor prognostic indicators include nonresectable or small cell primary tumors, multiple cutaneous metastases, or other distant metastases.[4] Mean survival is usually about 5–6 months.[10] FDG PET/CT is an established imaging modality in the identification of an unknown primary malignancy and also has an important role in the therapeutic decision-making. Inability to detect the primary leads to high treatment failures and futile neck dissections in patients with cervical lymphadenopathy.

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Conflicts of interest

There are no conflicts of interest.