A decreased male was brought to the morgue for a post-mortem examination. His relatives reported that he had a tattoo over his skin, which was not found on examination. Which of the following structures would you examine?

Correct Answer: D. Lymph nodes

When a tattoo is reported by relatives but not visible on external skin examination during post-mortem, the examiner must search for evidence of the tattoo in regional lymph nodes. Tattoo pigments (typically carbon, iron oxide, or organic dyes) are not confined to the dermis—they are phagocytosed by macrophages and transported via lymphatic drainage to regional lymph nodes, where they accumulate over time. This creates a characteristic discoloration or pigmentation of the draining lymph nodes (e.g., axillary nodes for arm tattoos, inguinal nodes for leg tattoos). The tattoo may have disappeared from skin due to: (1) decomposition and sloughing of skin in advanced putrefaction, (2) post-mortem artifact or trauma, (3) chemical dissolution of pigment, or (4) skeletonization. However, the pigment deposited in lymph nodes persists much longer and serves as forensic evidence of the tattoo's existence. This principle is taught in forensic pathology as a method of identification when external marks are lost. Examining lymph nodes is therefore the correct forensic approach to confirm a reported tattoo when skin examination is inconclusive.

Why the other options are wrong

A. Arteries — Arteries do not accumulate tattoo pigment. While tattoo pigments may be transported via blood circulation, they are not selectively deposited or retained in arterial walls in a manner that would serve forensic identification. The lymphatic system, not the arterial system, is the primary route of pigment transport and deposition in regional nodes. B. Liver — The liver is not the primary site of tattoo pigment accumulation. Although some systemic absorption of pigment may occur, the liver does not show characteristic discoloration from tattoo pigments in a way that would aid identification. Regional lymph nodes draining the tattoo site are far more reliable and specific for forensic evidence. C. Skin — This is the NBE trap. The question explicitly states the tattoo was 'not found on examination' of skin. Skin examination has already been performed and is negative. The examiner must look beyond the skin to regional lymph nodes where pigment persists even after skin decomposition or loss.

High-Yield Facts

Mnemonics

LYMPH for Lost Tattoos Lymphatic drainage carries pigment → Yield regional nodes → Macrophages phagocytose dye → Pigment persists in nodes → Helps identify when skin is gone. Use this when skin evidence is lost but relatives report a tattoo. Regional Node Rule Tattoo → Lymph → Regional Node. Always examine the lymph node basin that drains the anatomical region where the tattoo was reported (arm tattoo → axillary nodes; leg tattoo → inguinal nodes).

NBE Trap

NBE pairs "tattoo not found on skin" with the obvious choice of "examine skin again," luring students into option C. The trap is that the question already states skin examination was negative—the examiner must pivot to the lymphatic system where pigment persists as forensic evidence.

Clinical Pearl

In Indian morgues, this principle is critical during monsoon season when rapid putrefaction and skin sloughing occur. A tattoo reported by family members as identification may be completely absent from skin within 48–72 hours of death, but regional lymph node examination will still reveal the characteristic pigmentation, confirming identity and corroborating the family's account.

_Reference: Forensic Medicine & Toxicology (Reddy, 3rd edition), Chapter on Identification; Parikh's Textbook of Medical Jurisprudence, Forensics and Toxicology, Chapter on Identification of Human Remains_