OPEN ACCESS

CASE REPORT

Large Diffuse Cutaneous Metastases Secondary to Rectal

Mucinous Adenocarcinoma

Agustín A. Alesandrini¹, Isidro Moggiano², Juan A. Perriello¹, Tomás F. Ferrer Quiroga²

¹Colorectal Surgeon

²General Surgery Resident

Hospital Privado de La Comunidad, Mar del Plata, Argentina

ABSTRACT

Cutaneous metastases as the initial manifestation of colorectal cancer are rare, with an incidence below 1%. They usually occur

in patients with advanced disease and may present with variable clinical features mimicking infectious conditions. Early recognition

is essential for timely diagnosis and appropriate management.

We report the case of an immunosuppressed kidney transplant recipient who developed cutaneous lesions initially suspected to

be herpes zoster. Owing to the lack of response to antiviral therapy, a skin biopsy was performed and revealed metastatic

mucinous carcinoma. Immunohistochemical findings supported a colorectal origin, and imaging studies identified a primary rectal

tumor with metastatic disease.

To cite:

Alesandrini AA, Moggiano I, Perriello JA,

Ferrer Quiroga Tomás F. Large Diffuse

Cutaneous Metastases Secondary to Rectal

Mucinous Adenocarcinoma. Rev Argent

Coloproctol. 2026; 37(2):25-28.

doi:10.46768/bzhrdb11

This case highlights the importance of including cutaneous metastases in the differential diagnosis of atypical skin lesions,

particularly in immunocompromised patients, and underscores the pivotal role of biopsy and immunohistochemistry in identifying

neoplasms of initially unknown origin.

Additional supplemental material, when

applicable, is published online only. To view,

please visit the journal online:

https://doi.org/10.46768/bzhrdb11

Keywords: cutaneous metastases; colorectal cancer; mucinous adenocarcinoma; immunosuppression; herpes zoster

Received: November 10, 2025

Accepted: April 28, 2026

evaluation. She was receiving immunosuppressive

INTRODUCTION

therapy with sirolimus (2 mg/day) and

methylprednisolone (4 mg/day). Her medical history

Cutaneous metastases from colorectal cancer are an

was also notable for neuropathy, peripheral arterial

uncommon manifestation, with a reported incidence

disease, and right above-knee amputation.

of less than 1% among affected patients.^1–3Within

The patient presented with painful vesicular lesions

the spectrum of cutaneous metastases arising from

involving the right lower extremity stump, initially

solid tumors, colorectal cancer represents

interpreted as herpes zoster in the setting of

immunosuppression (Fig. 1). However, because of

the lack of response to antiviral therapy and

relatively rare etiology compared with malignancies

more commonly associated with skin involvement,

such as breast and lung cancer.³

persistence of the lesions,

performed.

skin biopsy was

Clinically, these lesions demonstrate marked

morphologic heterogeneity. They may present as

firm subcutaneous nodules, infiltrative plaques, or,

less frequently, as atypical lesions mimicking

infectious processes such as herpes zoster.⁴ This

broad clinical spectrum may complicate diagnosis

and delay appropriate treatment, particularly in

immunocompromised patients.

Histopathologic examination revealed dermal

infiltration by neoplastic cells suspended within

abundant extracellular mucin, forming characteristic

mucin pools consistent with mucinous carcinoma

(Fig.

2).

Immunohistochemical

analysis

demonstrated positivity for cytokeratins AE1/AE3,

CK20, and CDX2, and negativity for CK7, TTF1,

PAX8, CD10, and GATA3, findings consistent with

cutaneous metastasis of colorectal origin.

Given the suspicion of metastatic disease from an

initially unknown primary tumor, CT of the chest,

abdomen, and pelvis was performed, demonstrating

irregular mural thickening of the lower rectum,

The presence of cutaneous metastases generally

reflects advanced systemic dissemination and is

associated with a poor prognosis, with a reported

median survival of less than 1 year from the time of

2026 The authors. Published by Revista

Argentina de Coloproctología. This article is

distributed under the Creative Commons

Attribution–NonCommercial–NoDerivatives

4.0 International License (CC BY-NC-ND

4.0)

diagnosis.⁴ ⁵ In this setting, early recognition is

essential, as it may facilitate timely therapeutic

optimization and guide appropriate clinical

management.

Mucinous rectal carcinoma represents a distinct

histologic subtype characterized by abundant

extracellular mucin production and unique biologic

mesorectal,

retroperitoneal,

and

inguinal

https://creativecommons.org/licenses/by-

nc-nd/4.0/

lymphadenopathy measuring up to 26 mm (Fig. 3),

as well as multiple pulmonary nodules suggestive of

metastatic disease.

Endoscopic evaluation and rectal MRI were not

performed due to the patient’s clinical condition and

the confirmed tumor origin based on histopathologic

and imaging findings.

Microsatellite instability testing was not performed

because the patient was not considered a candidate

for immunotherapy given her immunosuppressed

status.

behavior, including

greater propensity for

peritoneal dissemination and differential therapeutic

response patterns compared with conventional

adenocarcinoma.⁶ Although cutaneous involvement

is exceedingly rare, its recognition may represent the

first manifestation of metastatic disease or tumor

progression.

Correspondence to

Agustín A. AlesandrinI

agustinalesandrini91@gmail.com

The case was discussed at a multidisciplinary tumor

board, and systemic treatment with capecitabine was

initiated. After 3 cycles of chemotherapy, disease

stabilization was observed in both the cutaneous

lesions and the primary tumor. However, tumor

progression was confirmed 8 months after diagnosis,

leading to a transition to palliative and symptom-

directed care. The patient died 11 months after the

initial diagnosis.

CASE

An 81-year-old woman with a medical history

significant for hypertension, chronic kidney disease

secondary to polycystic kidney disease, and

deceased-donor kidney transplantation performed in

2011 with preserved graft function presented for

REV ARGENT COLOPROCT | 2026 | VOL 37, No. 2

CASE REPORT

infections are more prevalent. In the present case, the initial

suspicion of herpes zoster in a renal transplant recipient illustrates

this diagnostic challenge.

Immunosuppression is a relevant factor in this context, not only

due to the increased risk of de novo malignancies in transplant

recipients, but also because of the potential for atypical and more

aggressive clinical presentations.¹⁰This underscores the

importance of maintaining a high index of suspicion for persistent

or atypically evolving cutaneous lesions in this population.

Histopathology and immunohistochemistry play a central role in

determining tumor origin, particularly when the primary tumor

has not been previously identified. The presence of mucin lakes

containing floating neoplastic cells, together with an

immunoprofile characterized by CK20 and CDX2 positivity and

CK7 negativity, supports a colorectal origin and helps exclude

other common primary sites such as lung, breast, kidney, or

gynecologic tumors.

Figure 1. Vesicular cutaneous lesions on the right lower extremity stump,

initially interpreted as herpes zoster.

DISCUSSION

Cutaneous metastases from colorectal carcinoma are an

uncommon manifestation, with a reported incidence of less than

1% of cases, and typically reflect advanced systemic disease.^1–3

In most patients, they occur in the setting of known metastatic

disease; therefore, their presentation as an initial manifestation or

as a finding leading to the diagnosis of the primary tumor is

exceptional.

From a clinical standpoint, colorectal cutaneous metastases most

frequently involve the abdominal wall, perineal region, and

surgical scars, a distribution associated with mechanisms of direct

extension or tumor implantation.^4,7However, less common sites

have also been reported, including the chest, head and neck, and

extremities; the latter represent a particularly rare presentation, as

observed in the present patient.⁷ ⁹

Figure 3. CT scan of the abdomen and pelvis showing irregular mural

thickening of the lower rectum with associated inguinal lymphadenopathy.

Regarding prognosis, the development of cutaneous metastases in

colorectal cancer is associated with limited survival, with

reported medians ranging from 5 to 12 months from diagnosis.^4,5

Although treatment of colorectal cutaneous metastases is

predominantly palliative,

multidisciplinary approach may

contribute to improved symptom control and quality of life. In the

present case, systemic chemotherapy with capecitabine initially

achieved disease stabilization; however, tumor progression was

subsequently observed at 8 months after diagnosis, with an

overall survival of 11 months, consistent with the published

literature.

This case adds several clinically relevant aspects to the existing

literature, including metastatic involvement of an extremity, a

pseudozosteriform clinical presentation, and the context of

immunosuppression in

highlights the importance

renal transplant recipient. It also

of integrating clinical,

histopathological, and imaging findings to achieve an accurate

diagnosis and guide appropriate therapeutic management.

CONCLUSIONS

The presence of atypical, persistent, or unusually evolving

cutaneous lesions, particularly in immunocompromised patients,

should raise suspicion for metastatic involvement, even when the

clinical presentation mimics common infectious entities such as

herpes zoster.

Skin biopsy, complemented by histopathologic and

immunohistochemical analysis, represents the key diagnostic tool

for determining tumor origin in neoplasms with an initially

unknown primary site.

Figure 2. Histopathology of the cutaneous lesion. A. Preserved epidermis

with dermal infiltration by neoplastic cells associated with abundant

extracellular mucin, consistent with mucinous adenocarcinoma (H&E,

40×). B. Tumor cells arranged in clusters within extracellular mucin

pools, showing vesicular nuclei and prominent nucleoli (H&E, 400×).

This case underscores the importance of a comprehensive

multidisciplinary diagnostic approach and the consideration of

uncommon differential diagnoses in atypical clinical

presentations. The integration of clinical, histopathological, and

imaging findings is essential to guide therapeutic decision-

While nodular lesions are the most common clinical presentation,

atypical variants that may mimic infectious or inflammatory

conditions, including zosteriform patterns, have also been

described.^4,8This phenomenon may lead to diagnostic delays,

particularly in immunocompromised patients, in whom cutaneous

DIFFUSE CUTANEOUS METASTASES SECONDARY TO RECTAL MUCINOUS ADENOCARCINOMA

Alesandrini AA, et al.

REV ARGENT COLOPROCT | 2026 | VOL 37, No. 2

CASE REPORT

2. Krathen RA, Orengo IF, Rosen T. Cutaneous metastasis: a meta-analysis

of data. South Med J. 2003;96(2):164–7.

3. Brenner M, Zalaudek I, Hofmann-Wellenhof R. Cutaneous metastases of

internal malignancies: an update. J Dtsch Dermatol Ges. 2020;18(8):816–

27.

making and optimize the management of patients with advanced

malignancy.

Author Contributions

4. Nashan D, Müller ML, Braun-Falco M, Reichenberger S, Szeimies RM,

Bruckner-Tuderman L. Cutaneous metastases of visceral tumours:

review. J Cancer Res Clin Oncol. 2009;135(1):1–14.

5. Wang DY, Ye F, Lin JJ, Xu X. Cutaneous metastasis: a rare phenomenon

of colorectal cancer. Ann Surg Treat Res. 2017;93(5):277–80.

6. Hugen N, van de Velde CJH, de Wilt JHW, Nagtegaal ID. Mucinous

colorectal carcinoma: clinical pathology and treatment options. Ann Surg

Oncol. 2015;22(11):3499–505.

7. Parente P, Ciardiello D, Reggiani Bonetti L, Famiglietti V, Cazzato G,

Caramaschi S, et al. Cutaneous metastasis from colorectal cancer: making

light on an unusual and misdiagnosed event. Life (Basel).

2021;11(9):954.doi: 10.3390/life11090954.

8. Chiang A, Hsu CK, Lee JY. Cutaneous metastasis mimicking herpes

zoster: a case report and review of the literature. Dermatol Online J.

2018;24(2):13030.

AAA: conceptualization, methodology, research, drafting of the original

manuscript, revision, and editing of the manuscript. IM: conceptualization,

methodology, research, drafting of the original manuscript. JAP: supervision,

project management, and manuscript revision. TFFQ: research, resources,

and collection and curation of material. All authors approved the final version

of the manuscript.

Conflict of interest statement: None

Funding: None

Data availability statement: The data are publicly available

ORCIDS

Agustin A. Alesandrini: 0000-0002-9821-8360

Isidro Moggiano: 0009-0006-2023-1430

Juan A. Perriello: 0000-0002-2739-7242

Tomás F. Ferrer Quiroga: 0009-0004-9361-6492

9. Zelenova E, Belysheva T, Sofronov D, Semenova V, Radjabova G,

Vishnevskaya Y, et al. Cutaneous metastasis of rectal cancer as a diagnostic

challenge:

clinical case and literature review. Diagnostics (Basel).

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DIFFUSE CUTANEOUS METASTASES SECONDARY TO RECTAL MUCINOUS ADENOCARCINOMA

Alesandrini AA, et al.